Selective removal process to create high aspect ratio fully self-aligned via

ABSTRACT

Apparatuses and methods to provide a fully self-aligned via are described. Some embodiments of the disclosure utilize a cap layer to protect an insulating layer in order to minimize bowing of the side walls during metal recess in a fully self-aligned via. The cap layer can be selectively removed, thus increasing the aspect ratio, by exposing the substrate to a hot phosphoric acid solution.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/668,406, filed May 8, 2018, the entire disclosure of which is herebyincorporated by reference herein.

TECHNICAL FIELD

Embodiments of the present disclosure pertain to the field of electronicdevice manufacturing, and in particular, to an integrated circuit (IC)manufacturing. More particularly, embodiments of the disclosure aredirected to methods of producing vias which are self-aligned such thatconductive layers with lines running in opposing directions areconnected.

BACKGROUND

Generally, an integrated circuit (IC) refers to a set of electronicdevices, e.g., transistors formed on a small chip of semiconductormaterial, typically, silicon. Typically, the IC includes one or morelayers of metallization having metal lines to connect the electronicdevices of the IC to one another and to external connections. Typically,layers of the interlayer dielectric material are placed between themetallization layers of the IC for insulation.

As the size of the IC decreases, the spacing between the metal linesdecreases. Typically, to manufacture an interconnect structure, a planarprocess is used that involves aligning and connecting one layer ofmetallization to another layer of metallization.

Typically, patterning of the metal lines in the metallization layer isperformed independently from the vias above that metallization layer.Conventional via manufacturing techniques, however, cannot provide thefull via self-alignment. In the conventional techniques, the vias formedto connect lines in an upper metallization layer to a lowermetallization are often misaligned to the lines in the lowermetallization layer. The via-line misalignment increases via resistanceand leads to potential shorting to the wrong metal line. The via-linemisalignment causes device failures, decreases yield and increasesmanufacturing cost.

SUMMARY

Apparatuses and methods to provide a fully self-aligned via aredescribed. In one embodiment, a first metallization layer comprises aset of first conductive lines that extend along a first direction, eachof the first conductive lines separated from an adjacent firstconductive line by a first insulating layer. An etch stop layer is onthe first insulating layer, and a second insulating layer is on thefirst insulating layer, the second insulating layer separated from thefirst insulating layer by the etch stop layer. A third insulating layeris on some of the first conductive lines so that at least one conductiveline is free of the third insulating layer. A second metallization layeris on portions of the second insulating layer and the third insulatinglayer, the second metallization layer comprising a set of secondconductive lines extending along a second direction that crosses thefirst direction at an angle, each of the second conductive linesseparated from an adjacent second conductive line by a fourth insulator.At least one via is between the first metallization layer and the secondmetallization layer, each of the at least one vias formed on the atleast one first conductive line that is free of the third insulatinglayer and having a conductive material therein, wherein the via isself-aligned along the second direction to one of the first conductivelines.

One or more embodiments are directed to methods to provide a fullyself-aligned via. A substrate is provided having a first insulatinglayer thereon, the first insulating layer having a top surface with aplurality of trenches formed along a first direction. A cap layer isformed on the top surface of the first insulating layer. A plurality ofrecessed first conductive lines are provided in the trenches of thefirst insulating layer, the first conductive lines extending along thefirst direction and having a first conductive surface below the topsurface of the first insulating layer. A first metal film is formed onthe recessed first conductive lines. Pillars are formed from the firstmetal film on the recessed first conductive lines, the pillars extendingorthogonal to the top surface of the first insulating layer. At least aportion of the cap layer is selectively removed to expose the topsurface of the first insulating layer. A second insulating layer isdeposited around the pillars and on the top surface of the firstinsulating layer. At least one of the pillars is selectively removed toform at least one opening in the second insulating layer. A thirdinsulating layer is deposited in the openings onto the recessed firstconductive lines to form filled vias. A portion of the third insulatinglayer is etched relative to the second insulating layer to form a viaopening to at least one of the first conductive lines. Second conductivelines are then formed on portions of the second insulating layer and thethird insulating layer, the second conductive lines extending along asecond direction that crosses the first direction at an angle.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments. The embodiments as described herein areillustrated by way of example and not limitation in the figures of theaccompanying drawings in which like references indicate similarelements.

FIG. 1A illustrates a top view and a cross-sectional view of anelectronic device structure to provide a fully self-aligned viaaccording to one embodiment.

FIG. 1B is a perspective view of the electronic device structuredepicted in FIG. 1A.

FIG. 2 is a view similar to FIG. 1A, after the conductive lines arerecessed according to one embodiment.

FIG. 3 is a view similar to FIG. 2, after a liner is deposited on therecessed conductive lines according to one embodiment.

FIG. 4 is a view similar to FIG. 3, after a seed gapfill layer isdeposited on the liner according to one embodiment.

FIG. 5 is a view similar to FIG. 4, after portions of the seed gapfilllayer are removed to expose top portions of the insulating layeraccording to one embodiment.

FIG. 6 is a view similar to FIG. 5, after self-aligned selective growthpillars are formed according to one embodiment.

FIG. 7 is a view similar to FIG. 6 after a cap layer is removedaccording to one embodiment.

FIG. 8 is a view similar to FIG. 7 after an insulating layer isdeposited to overfill the gaps between the pillars according to oneembodiment.

FIG. 9 is a view similar to FIG. 8, after a portion of the insulatinglayer is removed to expose the top portions of the pillars according toone embodiment.

FIG. 10 is a view similar to FIG. 9 after the self-aligned selectivelygrown pillars are selectively removed to form trenches according to oneembodiment.

FIG. 11 is a view similar to FIG. 10 after an insulating layer isdeposited into trenches according to one embodiment.

FIG. 12 is a view after an insulating layer is deposited into trenchesaccording to one embodiment.

FIG. 13A is a view similar to FIG. 12 after a mask layer is deposited onan insulating layer on the patterned hard mask layer according to oneembodiment.

FIG. 13B is a cross-sectional view of FIG. 13A along an axis C-C′.

FIG. 14A is a view similar to FIG. 13B after the insulating layer isselectively etched according to one embodiment.

FIG. 14B is a view similar to FIG. 13A after the insulating layer isselectively etched according to one embodiment.

FIG. 15A is a view similar to FIG. 11 after a mask layer is deposited ona hard mask layer according to one embodiment.

FIG. 15B is a top view of the electronic device structure depicted inFIG. 15A.

FIG. 16A is a view similar to FIG. 15A after portions of the hard masklayer and the insulating layer are removed according to one embodiment.

FIG. 16B is a top view of the electronic device structure depicted inFIG. 16A.

FIG. 17A is a view similar to FIG. 16A after a fully self-alignedopening is formed in insulating layer according to one embodiment.

FIG. 17B is a top view of the electronic device structure depicted inFIG. 17A.

FIG. 18A is a view similar to FIG. 17A after an upper metallizationlayer comprising conductive lines extending along a Y-axis is formedaccording to one embodiment.

FIG. 18B is a top view of the electronic device structure depicted inFIG. 18A.

FIG. 19A is a view similar to FIG. 11 after a mask layer is deposited ona hard mask layer according to one embodiment.

FIG. 19B is a top view of the electronic device structure depicted inFIG. 19A.

FIG. 20A is a view similar to FIG. 19A after portions of the hard masklayer and the insulating layer are removed according to one embodiment.

FIG. 20B is a top view of the electronic device structure depicted inFIG. 20A.

FIG. 21A is a view similar to FIG. 20A after forming a planarizationfilling layer and mask layer according to one embodiment.

FIG. 21B is a top view of the electronic device structure depicted inFIG. 21A.

FIG. 22A is a view similar to FIG. 21A after a fully self-alignedopening is formed in insulating layer according to one embodiment.

FIG. 22B is a top view of the electronic device structure depicted inFIG. 22A.

FIG. 23A is a view similar to FIG. 22A after an upper metallizationlayer comprising conductive lines extending along a Y-axis is formedaccording to one embodiment.

FIG. 23B is a top view of the electronic device structure depicted inFIG. 23A.

FIG. 24 shows a block diagram of a plasma system to provide a fullyself-aligned via according to one embodiment.

FIG. 25A illustrates a top view and a cross-sectional view of anelectronic device structure to provide a fully self-aligned viaaccording to an alternate embodiment.

FIG. 25B is a perspective view of the electronic device structuredepicted in FIG. 25A.

FIG. 26 is a view similar to FIG. 25A, after the conductive lines arerecessed according to one embodiment.

FIG. 27 is a view similar to FIG. 26, after a liner is deposited on therecessed conductive lines according to one embodiment.

FIG. 28 is a view similar to FIG. 27, after a seed gapfill layer isdeposited on the liner according to one embodiment.

FIG. 29 is a view similar to FIG. 28, after portions of the seed gapfilllayer are removed to expose top portions of the insulating layeraccording to one embodiment.

FIG. 30 is a view similar to FIG. 29, after self-aligned selectivegrowth pillars are formed according to one embodiment.

FIG. 31 is a view similar to FIG. 30 after a cap layer is removedaccording to one embodiment.

FIG. 32 is a view similar to FIG. 31 after an insulating layer isdeposited to overfill the gaps between the pillars according to oneembodiment.

FIG. 33A is a view similar to FIG. 32, after a portion of the insulatinglayer is removed to expose the top portions of the pillars according toone embodiment.

FIG. 33B is a view similar to FIG. 32, after an insulating layer isdeposited to underfill the gaps between the pillars according to anotherembodiment.

FIG. 34 is a view similar to FIG. 33A after the self-aligned selectivelygrown pillars are selectively removed to form trenches according to oneembodiment.

FIG. 35 is a view similar to FIG. 34 after an insulating layer isdeposited into trenches according to one embodiment.

FIG. 36 is a view after an insulating layer is deposited into trenchesaccording to one embodiment.

FIG. 37A is a view similar to FIG. 36 after a mask layer is deposited onan insulating layer on the patterned hard mask layer according to oneembodiment.

FIG. 37B is a cross-sectional view of FIG. 37A along an axis F-F′.

FIG. 38A is a view similar to FIG. 37B after the insulating layer isselectively etched according to one embodiment.

FIG. 38B is a view similar to FIG. 37A after the insulating layer isselectively etched according to one embodiment.

FIG. 39A is a view similar to FIG. 35 after a mask layer is deposited ona hard mask layer according to one embodiment.

FIG. 39B is a top view of the electronic device structure depicted inFIG. 39A.

FIG. 40A is a view similar to FIG. 39A after portions of the hard masklayer and the insulating layer are removed according to one embodiment.

FIG. 40B is a top view of the electronic device structure depicted inFIG. 40A.

FIG. 41A is a view similar to FIG. 40A after a fully self-alignedopening is formed in insulating layer according to one embodiment.

FIG. 41B is a top view of the electronic device structure depicted inFIG. 41A.

FIG. 42A is a view similar to FIG. 41A after an upper metallizationlayer comprising conductive lines extending along a Y-axis is formedaccording to one embodiment.

FIG. 42B is a top view of the electronic device structure depicted inFIG. 42A.

FIG. 43A is a view similar to FIG. 35 after a mask layer is deposited ona hard mask layer according to one embodiment.

FIG. 43B is a top view of the electronic device structure depicted inFIG. 43A.

FIG. 44A is a view similar to FIG. 43A after portions of the hard masklayer and the insulating layer are removed according to one embodiment.

FIG. 44B is a top view of the electronic device structure depicted inFIG. 44A.

FIG. 45A is a view similar to FIG. 45A after forming a planarizationfilling layer and mask layer according to one embodiment.

FIG. 45B is a top view of the electronic device structure depicted inFIG. 45A.

FIG. 46A is a view similar to FIG. 45A after a fully self-alignedopening is formed in insulating layer according to one embodiment.

FIG. 46B is a top view of the electronic device structure depicted inFIG. 46A.

FIG. 47A is a view similar to FIG. 46A after an upper metallizationlayer comprising conductive lines extending along a Y-axis is formedaccording to one embodiment.

FIG. 47B is a top view of the electronic device structure depicted inFIG. 47A.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, amorphous silicon, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal and/or bake the substratesurface. In addition to film processing directly on the surface of thesubstrate itself, in the present disclosure, any of the film processingsteps disclosed may also be performed on an under-layer formed on thesubstrate as disclosed in more detail below, and the term “substratesurface” is intended to include such under-layer as the contextindicates. Thus for example, where a film/layer or partial film/layerhas been deposited onto a substrate surface, the exposed surface of thenewly deposited film/layer becomes the substrate surface.

As used in this specification and the appended claims, the terms“precursor”, “reactant”, “reactive gas” and the like are usedinterchangeably to refer to any gaseous species that can react with thesubstrate surface.

Methods and apparatus to provide fully self-aligned vias are described.In one embodiment, a first metallization layer comprises a set of firstconductive lines that extend along a first direction, each of the firstconductive lines separated from an adjacent first conductive line by afirst insulating layer. An etch stop layer is on the first insulatinglayer, and a second insulating layer is on the first insulating layer,the second insulating layer separated from the first insulating layer bythe etch stop layer. A third insulating layer is on some of the firstconductive lines so that at least one conductive line is free of thethird insulating layer. A second metallization layer is on portions ofthe second insulating layer and the third insulating layer, the secondmetallization layer comprising a set of second conductive linesextending along a second direction that crosses the first direction atan angle, each of the second conductive lines separated from an adjacentsecond conductive line by a fourth insulator. At least one via isbetween the first metallization layer and the second metallizationlayer, each of the at least one vias formed on the at least one firstconductive line that is free of the third insulating layer and having aconductive material therein, wherein the via is self-aligned along thesecond direction to one of the first conductive lines.

In one embodiment, the via is self-aligned along the first direction toone of the second conductive lines.

In one embodiment, a fully self-aligned via is the via that isself-aligned along at least two directions to the conductive lines in alower (or first) and an upper (or second) metallization layer. In oneembodiment, the fully self-aligned via is defined by a hard mask in onedirection and the underlying insulating layer in another direction, asdescribed in further detail below.

Comparing to the conventional techniques, some embodimentsadvantageously provide fully self-aligned vias with minimized bowing ofthe side walls during metal recess. In some embodiments, the fullyself-aligned vias provide lower via resistance and capacitance benefitsover the conventional vias. Some embodiments of the self-aligned viasprovide full alignment between the vias and the conductive lines of themetallization layers that is substantially error free thatadvantageously increase the device yield and reduce the device cost.Additionally, some embodiments of the self-aligned vias provide a highaspect ratio for the fully self-aligned via.

In the following description, numerous specific details, such asspecific materials, chemistries, dimensions of the elements, etc. areset forth in order to provide thorough understanding of one or more ofthe embodiments of the present disclosure. It will be apparent, however,to one of ordinary skill in the art that the one or more embodiments ofthe present disclosure may be practiced without these specific details.In other instances, semiconductor fabrication processes, techniques,materials, equipment, etc., have not been descried in great details toavoid unnecessarily obscuring of this description. Those of ordinaryskill in the art, with the included description, will be able toimplement appropriate functionality without undue experimentation.

While certain exemplary embodiments of the disclosure are described andshown in the accompanying drawings, it is to be understood that suchembodiments are merely illustrative and not restrictive of the currentdisclosure, and that this disclosure is not restricted to the specificconstructions and arrangements shown and described because modificationsmay occur to those ordinarily skilled in the art.

Reference throughout the specification to “one embodiment”, “anotherembodiment”, or “an embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in a least one embodiment of the present disclosure. Thus,the appearance of the phrases “in one embodiment” or “in an embodiment”in various places throughout the specification are not necessarily allreferring to the same embodiment of the disclosure. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more embodiments.

FIG. 1A illustrates a top view 100 and a cross-sectional view 112 of anelectronic device 114 structure to provide a fully self-aligned viaaccording to one embodiment. The cross-sectional view 112 is along anaxis A-A′, as depicted in FIG. 1A. FIG. 1B is a perspective view 120 ofthe electronic device structure depicted in FIG. 1A. A lowermetallization layer (Mx) comprises a set of conductive lines 106 thatextend along an X-axis (direction) 122 on an insulating layer 104 on asubstrate 102, as shown in FIGS. 1A and 1B. As shown in FIG. 1B, X-axis(direction) 122 crosses Y-axis (direction) 124 at an angle 126. In oneembodiment, angle 126 is about 90 degrees. In another embodiment, angle126 is an angle that is other than the 90 degrees angle. The insulatinglayer 104 comprises trenches 108. The conductive lines 106 are depositedin trenches 108. A cap layer 110 is formed on the insulating layer 104.

In an embodiment, the substrate 102 comprises a semiconductor material,e.g., silicon (Si), carbon (C), germanium (Ge), silicon germanium(SiGe), gallium arsenide (GaAs), indium phosphide (InP), indium galliumarsenide (InGaAs), aluminum indium arsenide (InAlAs), othersemiconductor material, or any combination thereof. In an embodiment,substrate 102 is a semiconductor-on-isolator (SOI) substrate including abulk lower substrate, a middle insulation layer, and a topmonocrystalline layer. The top monocrystalline layer may comprise anymaterial listed above, e.g., silicon. In various embodiments, thesubstrate 102 can be, e.g., an organic, a ceramic, a glass, or asemiconductor substrate. Although a few examples of materials from whichthe substrate 102 may be formed are described here, any material thatmay serve as a foundation upon which passive and active electronicdevices (e.g., transistors, memories, capacitors, inductors, resistors,switches, integrated circuits, amplifiers, optoelectronic devices, orany other electronic devices) may be built falls within the spirit andscope of the present disclosure.

In one embodiment, substrate 102 includes one or more metallizationinterconnect layers for integrated circuits. In at least someembodiments, the substrate 102 includes interconnects, for example,vias, configured to connect the metallization layers. In at least someembodiments, the substrate 102 includes electronic devices, e.g.,transistors, memories, capacitors, resistors, optoelectronic devices,switches, and any other active and passive electronic devices that areseparated by an electrically insulating layer, for example, aninterlayer dielectric, a trench insulation layer, or any otherinsulating layer known to one of ordinary skill in the art of theelectronic device manufacturing. In one embodiment, the substrate 102includes one or more layers above substrate 102 to confine latticedislocations and defects.

Insulating layer 104 can be any material suitable to insulate adjacentdevices and prevent leakage. In one embodiment, electrically insulatinglayer 104 is an oxide layer, e.g., silicon dioxide, or any otherelectrically insulating layer determined by an electronic device design.In one embodiment, insulating layer 104 comprises an interlayerdielectric (ILD). In one embodiment, insulating layer 104 is a low-kdielectric that includes, but is not limited to, materials such as,e.g., silicon dioxide, silicon oxide, carbon doped oxide (“CDO”), e.g.,carbon doped silicon dioxide, porous silicon dioxide (SiO₂), siliconnitride (SiN), or any combination thereof.

In one embodiment, insulating layer 104 includes a dielectric materialhaving a k-value less than 5. In one embodiment, insulating layer 104includes a dielectric material having a k-value less than 2. In at leastsome embodiments, insulating layer 104 includes oxides, carbon dopedoxides, porous silicon dioxide, carbides, oxycarbides, nitrides,oxynitrides, oxycarbonitrides, polymers, phosphosilicate glass,fluorosilicate (SiOF) glass, organosilicate glass (SiOCH), or anycombinations thereof, other electrically insulating layer determined byan electronic device design, or any combination thereof. In at leastsome embodiments, insulating layer 104 may include polyimide, epoxy,photodefinable materials, such as benzocyclobutene (BCB), and WPR-seriesmaterials, or spin-on-glass.

In one embodiment, insulating layer 104 is a low-k interlayer dielectricto isolate one metal line from other metal lines on substrate 102. Inone embodiment, the thickness of the insulating layer 104 is in anapproximate range from about 10 nanometers (nm) to about 2 microns (μm).

In an embodiment, insulating layer 104 is deposited using one ofdeposition techniques, such as but not limited to a chemical vapordeposition (“CVD”), a physical vapor deposition (“PVD”), molecular beamepitaxy (“MBE”), metalorganic chemical vapor deposition (“MOCVD”),atomic layer deposition (“ALD”), spin-on, or other insulating depositiontechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing.

In one embodiment, the lower metallization layer Mx comprisingconductive lines 106 (i.e., metal lines) is a part of a back endmetallization of the electronic device. In one embodiment, theinsulating layer 104 is patterned and etched using a hard mask to formtrenches 108 using one or more patterning and etching techniques knownto one of ordinary skill in the art of microelectronic devicemanufacturing. In one embodiment, the size of trenches 108 in theinsulating layer 104 is determined by the size of conductive linesformed later on in a process.

In one embodiment, forming the conductive lines 106 involves filling thetrenches 108 with a layer of conductive material. In one embodiment, abase layer (not shown) is first deposited on the internal sidewalls andbottom of the trenches 108, and then the conductive layer is depositedon the base layer. In one embodiment, the base layer includes aconductive seed layer (not shown) deposited on a conductive barrierlayer (not shown). The seed layer can include copper (Cu), and theconductive barrier layer can include aluminum (Al), titanium (Ti),tantalum (Ta), tantalum nitride (TaN), and the like metals. Theconductive barrier layer can be used to prevent diffusion of theconductive material from the seed layer, e.g., copper or cobalt, intothe insulating layer 104. Additionally, the conductive barrier layer canbe used to provide adhesion for the seed layer (e.g., copper).

In one embodiment, to form the base layer, the conductive barrier layeris deposited onto the sidewalls and bottom of the trenches 108, and thenthe seed layer is deposited on the conductive barrier layer. In anotherembodiment, the conductive base layer includes the seed layer that isdirectly deposited onto the sidewalls and bottom of the trenches 108.Each of the conductive barrier layer and seed layer may be depositedusing any think film deposition technique known to one of ordinary skillin the art of semiconductor manufacturing, e.g., sputtering, blanketdeposition, and the like. In one embodiment, each of the conductivebarrier layer and the seed layer has the thickness in an approximaterange from about 1 nm to about 100 nm. In one embodiment, the barrierlayer may be a thin dielectric that has been etched to establishconductivity to the metal layer below. In one embodiment, the barrierlayer may be omitted altogether and appropriate doping of the copperline may be used to make a “self-forming barrier”.

In one embodiment, the conductive layer e.g., copper or cobalt, isdeposited onto the seed layer of base layer of copper, by anelectroplating process. In one embodiment, the conductive layer isdeposited into the trenches 108 using a damascene process known to oneof ordinary skill in the art of microelectronic device manufacturing. Inone embodiment, the conductive layer is deposited onto the seed layer inthe trenches 108 using a selective deposition technique, such as but notlimited to electroplating, electrolysis, CVD, PVD, MBE, MOCVD, ALD,spin-on, or other deposition techniques know to one of ordinary skill inthe art of microelectronic device manufacturing.

In one embodiment, the choice of a material for conductive layer for theconductive lines 106 determines the choice of a material for the seedlayer. For example, if the material for the conductive lines 106includes copper, the material for the seed layer also includes copper.In one embodiment, the conductive lines 106 include a metal, forexample, copper (Cu), ruthenium (Ru), nickel (Ni), cobalt (Co), chromium(Cr), iron (Fe), manganese (Mn), titanium (Ti), aluminum (Al), hafnium(Hf), tantalum (Ta), tungsten (W), vanadium (V), molybdenum (Mo),palladium (Pd), gold (Au), silver (Ag), platinum (Pt), indium (In), tin(Sn), lead (Pd), antimony (Sb), bismuth (Bi), zinc (Zn), cadmium (Cd),or any combination thereof.

In alternative embodiments, examples of the conductive materials thatmay be used for the conductive lines 106 of the metallization layer Mxare, for example, metals, e.g., copper (Cu), tantalum (Ta), tungsten(W), ruthenium (Ru), titanium (Ti), hafnium (Hf), zirconium (Zr),aluminum (Al), silver (Ag), tin (Sn), lead Pb), metal alloys, metalcarbides, e.g., hafnium carbide (HfC), zirconium carbide (ZrC), titaniumcarbide (TiC), tantalum carbide (TaC), aluminum carbide (AlC), otherconductive materials, or any combination thereof.

In one embodiment, portions of the conductive layer and the base layerare removed to even out top portions of the conductive lines 106 withtop portions of the insulating layer 104 using a chemical-mechanicalpolishing (“CMP”) technique known to one of ordinary skill in the art ofmicroelectronic device manufacturing.

In one non-limiting example, the thickness (as measured along the z-axisof FIG. 1A) of the conductive lines 106 is in an approximate range fromabout 15 nm to about 1000 nm. In one non-limiting example, the thicknessof the conductive lines 106 is from about 20 nm to about 200 nm. In onenon-limiting example, the width (as measured along the y-axis of FIG.1A) of the conductive lines 106 is in an approximate range from about 5nm to about 500 nm. In one non-limiting example, the spacing (pitch)between the conductive lines 106 is from about 2 nm to about 500 nm. Inmore specific non-limiting example, the spacing (pitch) between theconductive lines 106 is from about 5 nm to about 50 nm.

In an embodiment, the lower metallization layer Mx is configured toconnect to other metallization layers (not shown). In an embodiment, themetallization layer Mx is configured to provide electrical contact toelectronic devices, e.g., transistor, memories, capacitors, resistors,optoelectronic devices, switches, and any other active and passiveelectronic devices that are separated by an electrically insulatinglayer, for example, an interlayer dielectric, a trench insulation layer,or any other insulating layer known to one of ordinary skill in the artof electronic device manufacturing.

In one or more embodiments, the cap layer comprises silicon nitride(SiN). In one or more embodiments, the cap layer is selected from one ormore of silicon nitride (SiN), silicon oxide (SiO), silicon oxynitride(SiON), and silicon carbonitride (SiCN). The cap layer 110 protects theinsulating layer 104. In one or more embodiments, the cap layer 110minimizes bowing of the side walls of the trenches 108

FIG. 2 is a view 200 similar to cross-sectional view 112 of FIG. 1A,after the conductive lines 106 are recessed according to one embodiment.The conductive lines 106 are recessed to a predetermined depth to formrecessed conductive lines 202. As shown in FIG. 2, trenches 204 areformed in the insulating layer 104. Each trench 204 has sidewalls 206that are portions of insulating layer 104 and a bottom that is a topsurface 208 of the recessed conductive lines 202.

In one embodiment, the depth of the trenches 204 is from about 10 nm toabout 500 nm. In one embodiment, the depth of the trenches 204 is fromabout 10% to about 100% of the thickness of the conductive lines. In oneembodiment, the conductive lines 106 are recessed using one or more ofwet etching, dry etching, or a combination thereof techniques known toone of ordinary skill in the art of electronic device manufacturing.

FIG. 3 is a view 300 similar to FIG. 2, after a liner 302 is depositedon the recessed conductive lines 202 according to one embodiment. Liner302 is deposited on the bottom and sidewalls of the trenches 204, asshown in FIG. 3.

In one embodiment, liner 302 is deposited to protect the conductivelines 202 from changing properties later on in a process (e.g., duringtungsten deposition, or other processes). In one embodiment, liner 302is a conductive liner. In another embodiment, liner 302 is anon-conductive liner. In one embodiment, when liner 302 is anon-conductive liner, the liner 302 is removed later on in a process, asdescribed in further detail below. In one embodiment, liner 302 includestitanium nitride (TiN), titanium (Ti), tantalum (Ta), tantalum nitride(TaN), or any combination thereof. In another embodiment, liner 302 isan oxide, e.g., aluminum oxide (Al₂O₃), titanium oxide (TiO₂). In yetanother embodiment, liner 302 is a nitride, e.g., silicon nitride (SiN).In an embodiment, the liner 302 is deposited to the thickness from about0.5 nm to about 10 nm.

In an embodiment, the liner 302 is deposited using an atomic layerdeposition (ALD) technique. In one embodiment, the liner 302 isdeposited using one of deposition techniques, such as but not limited toa CVD, PVD, MBE, MOCVD, spin-on, or other liner deposition techniquesknow to one of ordinary skill in the art of microelectronic devicemanufacturing.

FIG. 4 is a view 400 similar to FIG. 3, after a seed gapfill layer 402is deposited on the liner 302 according to one embodiment. In oneembodiment, seed gapfill layer 402 is a self-aligned selective growthseed film. As shown in FIG. 4, seed gapfill layer 402 is deposited onliner 302 on the top surface 208 of the recessed conductive lines 202,the sidewalls 206 of the trenches 204 and top portions of the insulatinglayer 104. In one embodiment, seed gapfill layer 402 is a tungsten (W)layer, or other seed gapfill layer to provide selective growth pillars.In some embodiments, seed gapfill layer 402 is a metal film or a metalcontaining film. Suitable metal films include, but are not limited to,films including one or more of cobalt (Co), molybdenum (Mo), tungsten(W), tantalum (Ta), titanium (Ti), ruthenium (Ru), rhodium (Rh), copper(Cu), iron (Fe), manganese (Mn), vanadium (V), niobium (Nb), hafnium(Hf), zirconium (Zr), yttrium (Y), aluminum (Al), tin (Sn), chromium(Cr), lanthanum (La), or any combination thereof. In some embodiments,seed gapfill layer 402 comprises is a tungsten (W) seed gapfill layer.

In one embodiment, the seed gapfill layer 402 is deposited using one ofdeposition techniques, such as but not limited to an ALD, a CVD, PVD,MBE, MOCVD, spin-on or other liner deposition techniques known to one ofordinary skill in the art of microelectronic device manufacturing.

FIG. 5 is a view 500 similar to FIG. 4, after portions of the seedgapfill layer 402 are removed to expose top portions of the cap layer110 according to one embodiment. In one embodiment, the portions of theseed gapfill layer 402 are removed using one of the chemical-mechanicalpolishing (CMP) techniques known to one of ordinary skill in the art ofmicroelectronic device manufacturing.

FIG. 6 is a view 600 similar to FIG. 5, after self-aligned selectivegrowth pillars 602 are formed using the seed gapfill layer 402 on theliner 302 on the recessed conductive lines 202 according to oneembodiment. As shown in FIG. 6, an array of the self-aligned selectivegrowth pillars 602 has the same pattern as the set of the conductivelines 202. As shown in FIG. 6, the pillars 602 extend substantiallyorthogonally from the top surfaces of the conductive lines 202. As shownin FIG. 6, the pillars 602 extend along the same direction as theconductive lines 202. As shown in FIG. 6, the pillars are separated bygaps 606.

In one embodiment, the pillars 602 are selectively grown from the seedgapfill layer 402 on portions of the liner 302 on the conductive lines202. The pillars 602 are not grown on portions of the liner 302 on theinsulating layer 104, as shown in FIG. 6. In one embodiment, portions ofthe seed gapfill layer 402 above the conductive lines 202 are expandedfor example, by oxidation, nitridation, or other process to grow pillars602. In one embodiment, the seed gapfill layer 402 is oxidized byexposure to an oxidizing agent or oxidizing conditions to transform themetal or metal containing seed gapfill layer 402 to metal oxide pillars602. In one embodiment, pillars 602 include an oxide of one or moremetals listed above. In more specific embodiment, pillars 602 includetungsten oxide (e.g., WO, WO₃ and other tungsten oxide).

The oxidizing agent can be any suitable oxidizing agent including, butnot limited to, O₂, O₃, N₂O, H₂O, H₂O₂, CO, CO₂, N₂/Ar, N₂/He, N₂/Ar/He,ammonium persulphate, organic peroxide agents, such asmeta-chloroperbenzoic acid and peracids (e.g. trifluoroperacetic acid,2,4-dinitroperbenzoic acid, peracetic acid, persulfuric acid,percarbonic acid, perboric acid, and the like), or any combinationthereof. In some embodiments, the oxidizing conditions comprise athermal oxidation, plasma enhanced oxidation, remote plasma oxidation,microwave and radio-frequency oxidation (e.g., inductively coupledplasma (ICP), capacitively coupled plasma (CCP)).

In one embodiment, the pillars 602 are formed by oxidation of the seedgapfill layer at any suitable temperature depending on, for example, thecomposition of the seed gapfill layer and the oxidizing agent. In someembodiments, the oxidation occurs at a temperature in an approximaterange of about 25° C. to about 800° C. In some embodiments, theoxidation occurs at a temperature greater than or equal to about 150° C.

The pillars 602 form in a straight-up manner to grow a pillar that isorthogonal to the surface of the cap layer 110. As used in this manner,the term “orthogonal” means that a major plane formed by the sidewallsof the pillars 602 meet the surface of the cap layer 110 with a relativeangle in the range of about 75° to about 105°, or in the range of about80° to about 100°, or in the range of about 85° to about 95°, or about90°.

In one embodiment, the height 604 of the pillars 602 is in anapproximate range from about 5 angstroms (Å) to about 10 microns (μm).

FIG. 7 is a view 700 similar to FIG. 6, after at least a portion of thecap layer 110 is selectively removed to expose the top surface 702 ofthe insulating layer 104. The cap layer 110 can be removed by exposingthe substrate 102 to a solution of hot phosphoric acid (i.e. “hotphos”). In one or more embodiments, the entire cap layer 110 is removedby exposing the substrate 102 to a solution of hot phosphoric acid (hotphos). Without intending to be bound by theory, it is thought that thecap layer 110 serves as a sacrificial layer, introduced at the beginningof the process flow and removed midway to make the pillars appeartaller.

In one or more embodiments, the solution of hot phosphoric acid (hotphos) has a concentration in the range of 1 wt. % to 99 wt. % in water.In some embodiments, the phosphoric acid concentration is 1 wt. % to 99wt. %. The substrate 102 can be treated with the solution of hotphosphoric acid (hot phos) for a period in the range of 0.1 minutes to60 min. In some embodiments, the substrate 102 is treated with thesolution of hot phosphoric acid (hot phos) for a period in the range ofabout 2 seconds to about 2 hours, or about 2 seconds to about 1 hour. Inone or more embodiments, the temperature of the hot phosphoric acidsolution (hot phos) is in the range of 15° C. to 400° C. In someembodiments, the temperature of the hot phosphoric acid solution (hotphos) is in the range of 25° C. to 500° C. In some embodiments, thetemperature of the hot phosphoric acid solution (hot phos) is greaterthan 500° C.

In one or more embodiments, the removal of the cap layer 110 increasesthe aspect ratio. In one or more embodiments, the aspect ratio is in arange of 1:1 to 10:1.

It was unexpectedly and advantageously found by transmission electronmicroscopy (TEM) and electron energy loss spectroscopy (EELS) that thehot phos removal process is selective to the cap layer 110 and does notaffect the tungsten oxide layer.

FIG. 8 is a view 800 similar to FIG. 7, and, after an insulating layer802 is deposited to overfill the gaps 606 between the pillars 602according to one embodiment. As shown in FIG. 8, insulating layer 802 isdeposited on the opposing sidewalls 804 and top portions 806 of thepillars 602 and through the gaps 606 on the portions of the insulatinglayer 104 and liner 302 between the pillars 602.

In one embodiment, insulating layer 802 is a low-k gapfill layer. In oneembodiment, insulating layer 802 is a flowable silicon oxide (FSiOx)layer. In at least some embodiments, insulating layer 802 is an oxidelayer, e.g., silicon dioxide (SiO₂), or any other electricallyinsulating layer determined by an electronic device design. In oneembodiment, insulating layer 802 is an interlayer dielectric (ILD). Inone embodiment, insulating layer 802 is a low-k dielectric thatincludes, but is not limited to, materials such as, e.g., silicondioxide, silicon oxide, a carbon based material, e.g., a porous carbonfilm, carbon doped oxide (“CDO”), e.g. carbon doped silicon dioxide,porous silicon dioxide, porous silicon oxide carbide hydride (SiOCH),silicon nitride, or any combination thereof. In one embodiment,insulating layer 802 is a dielectric material having k-value less than3. In more specific embodiment, insulating layer 802 is a dielectricmaterial having k-value in an approximate range from about 2.2 to about2.7. In one embodiment, insulating layer 802 includes a dielectricmaterial having k-value less than 2. In one embodiment, insulating layer802 represents one of the insulating layers described above with respectto insulating layer 104.

In one embodiment, insulating layer 802 is a low-k interlayer dielectricto isolate one metal line from other metal lines. In one embodiment,insulating layer 802 is deposited using one of deposition techniques,such as but not limited to a CVD, spin-on, an ALD, PVD. MBE, MOCVD, orother low-k insulating layer deposition techniques known to one ofordinary skill in the art of microelectronic device manufacturing.

FIG. 9 is a view 900 similar to FIG. 8, after a portion of theinsulating layer 802 is removed to expose the top portions 806 of thepillars 602 according to one embodiment. In one embodiment, the portionof the insulating layer 802 is removed using a CMP technique known toone of ordinary skill in the art of microelectronic devicemanufacturing. In one embodiment, the portion of the insulating layer802 is etched back to expose the top portions 806 of the pillars 602using one or more of the dry and wet etching techniques known to one ofordinary skill in the art of microelectronic device manufacturing.

In one embodiment, insulating layer 802 is deposited using one ofdeposition techniques, such as but not limited to a CVD, spin-on, anALD, PVD, MBE, MOCVD, or other low-k insulating layer depositiontechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing. In another embodiment, insulating layer 802 isdeposited to overfill the gaps 606 between the pillars 602, as describedwith respect to FIG. 8, and then a portion of the insulating layer 802is etched back to expose upper portions 808 of the sidewalls 804 and topportions 806 of the pillars 602 using one or more of the dry and wetetching techniques known to one of ordinary skill in the art ofmicroelectronic device manufacturing.

FIG. 10 is a view 1000 similar to FIG. 9 after the self-alignedselectively grown pillars 602 are selectively removed to form trenches902 according to one embodiment. As shown in FIG. 10, the pillars 602are removed selectively to the insulating layer 802 and liner 302. Inanother embodiment, when liner 302 is a non-conductive liner, liner 302is removed. In one embodiment, the pillars 602 and liner 302 are removedselectively to the insulating layers 802 and 104 and conductive lines202. As shown in FIG. 10, trenches 902 are formed in the insulatinglayers 802 and 104. Trenches 902 extend along the recessed conductivelines 202. As shown in FIG. 10, each trench 902 has a bottom that is abottom portion 904 of liner 302 and opposing sidewalls that include asidewall portion 906 of liner 302 and a portion of insulating layer 802.In another embodiment, when liner 302 is removed, each trench 902 has abottom that is recessed conductive lines 202 and opposing sidewalls thatinclude portions of insulating layers 802 and 104. Generally, the aspectratio of the trench refers to the ratio of the depth of the trench tothe width of the trench. In one embodiment, the aspect ratio of eachtrench 902 is in an approximate range from about 1:1 to about 200:1.

In one embodiment, the pillars 602 are selectively removed using one ormore of the dry and wet etching techniques known to one of ordinaryskill in the art of electronic device manufacturing. In one embodiment,the pillars 602 are selectively wet etched by e.g., 5 wt. % of ammoniumhydroxide (NH₄OH) aqueous solution at the temperature of about 80degrees C. In one embodiment, hydrogen peroxide (H₂O₂) is added to the 5wt. % NH₄OH aqueous solution to increase the etching rate of the pillars602. In one embodiment, the pillars 602 are selectively wet etched usinghydrofluoric acid (HF) and nitric acid (HNO₃) in a ratio of 1:1. In oneembodiment, the pillars 602 are selectively wet etched using HF and HNO₃in a ratio of 3:7 respectively. In one embodiment, the pillars 602 areselectively wet etched using HF and HNO₃ in a ratio of 4:1,respectively. In one embodiment, the pillars 602 are selectively wetetched using HF and HNO₃ in a ratio of 30%:70%, respectively. In oneembodiment, the pillars 602 including tungsten (W), titanium (Ti), orboth titanium and tungsten are selectively wet etched using NH₄OH andH₂O₂ in a ratio of 1:2, respectively. In one embodiment, the pillars 602are selectively wet etched using 305 grams of potassium ferricyanide(K₃Fe(CN)₆), 44.5 grams of sodium hydroxide (NaOH) and 1000 ml of water(H₂O). In one embodiment, the pillars 602 are selectively wet etchedusing diluted or concentrated one or more of the chemistries includinghydrochloric acid (HCl), HNO₃, sulfuric acid (H₂SO₄), HF, and H₂O₂. Inone embodiment, the pillars 602 are selectively wet etched using HF,HNO₃ and acetic acid (CH₃COOH) in a ratio of 4:4:3, respectively. In oneembodiment, the pillars 602 are selectively dry etched using abromotrifluoromethane (CBrF3) reactive ion etching (RIE) technique. Inone embodiment, the pillars 602 are selectively dry etched using achlorine, fluorine, bromine or any combination thereof basedchemistries. In one embodiment, the pillars 602 are selectively wetetched using hot or warm Aqua Regia mixture including HCl and HNO₃ in aratio of 3:1, respectively. In one embodiment, the pillars 602 areselectively etched using alkali with oxidizers (potassium nitrate (KNO₃)and lead dioxide (PbO₂)). In one embodiment, the liner 302 isselectively removed using one or more of the dry and wet etchingtechniques known to one of ordinary skill in the art of electronicdevice manufacturing.

FIG. 11 is a view 1100 and that is similar to FIG. 10 after aninsulating layer 1102 is deposited into trenches 902 according to oneembodiment. As shown in FIG. 11, insulating layer 1102 overfills thetrenches 902 so that portions of the insulating layer 1102 are depositedon the top portions of the insulating layer 802. In one embodiment, thethickness of the insulating layer 1102 is greater or similar to thethickness of the insulating layer 802. In one embodiment, the thickness1104 is at least two or three times greater than the thickness of theinsulating layer 802. In another embodiment, portions of the insulatinglayer 1102 are removed using one or more of CMP or a back etch techniqueto even out with the top portions of the insulating layer 802, and thenother insulating layer (not shown) is deposited onto the top portions ofthe insulating layer 802 and insulating layer 1102. As shown in FIG. 11,insulating layer 1102 is deposited on the sidewalls and bottom of thetrenches 904. As shown in FIG. 11, the insulating layer 1102 isdeposited on the liner 302 and portions of the insulating layer 802. Inanother embodiment, when the liner 302 is removed, the insulating layer1102 is directly deposited on the recessed conductive lines 202 andportions of the insulating layer 104 and insulating layer 802. In oneembodiment, the insulating layer 1102 is etch selective to theinsulating layer 802. Generally, etch selectivity between two materialsis defined as the ratio between their etching rates at similar etchingconditions. In one embodiment, the ratio of the etching rate of theinsulating layer 1102 to that of the insulating layer 802 is at least5:1, 10:1, 15:1, 20:1 or 25:1. In one embodiment, the ratio of theetching rates of the insulating layer 1102 to that of the insulatinglayer 802 is in an approximate range from about 2:1 to about 50:1, or inthe range of about 3:1 to about 30:1, or in the range of about 4:1 toabout 20:1.

In one embodiment, insulating layer 1102 is a low-k gapfill layer. Inone embodiment, insulating layer 1102 is a flowable silicon oxidecarbide (FSiOC) layer. In some other embodiments, insulating layer 1102is an oxide layer, e.g., silicon dioxide, or any other electricallyinsulating layer determined by an electronic device design. In oneembodiment, insulating layer 1102 is an interlayer dielectric (ILD). Inone embodiment, insulating layer 1102 is a low-k dielectric thatincludes, but is not limited to, materials such as, e.g., silicondioxide, silicon oxide, a carbon based material, e.g., a porous carbonfilm carbon doped oxide (“CDO”), e.g., carbon doped silicon dioxide,porous silicon dioxide, porous silicon oxide carbide hydride (SiOCH),silicon nitride, or any combination thereof. In one embodiment,insulating layer 1102 is a dielectric material having k-value less than3. In more specific embodiment, insulating layer 1102 is a dielectricmaterial having k-value in an approximate range from about 2.2 to about2.7. In one embodiment, insulating layer 1102 includes a dielectricmaterial having k-value less than 2. In one embodiment, insulating layer1102 represents one of the insulating layers described above withrespect to insulating layer 104 and insulating layer 802.

In one embodiment, insulating layer 1102 is a low-k interlayerdielectric to isolate one metal line from other metal lines. In oneembodiment, insulating layer 1102 is deposited using one of depositiontechniques, such as but not limited to a CVD, spin-on, an ALD, PVD, MBE,MOCVD, or other low-k insulating layer deposition techniques known toone of ordinary skill in the art of microelectronic devicemanufacturing.

FIG. 12 is a view 1200 after a hard mask layer 1202 is deposited oninsulating layer 1204 according to one embodiment. FIG. 12 is differentfrom FIG. 11 in that the liner 302 is removed, so that insulating layer1204 is directly deposited on the recessed conductive lines 202 andportions of the insulating layer 104 and insulating layer 802, asdescribed above. In one embodiment, hard mask layer 1202 is ametallization layer hard mask. As shown in FIG. 11, the hard mask layer1202 is patterned to define a plurality of trenches 1206. As shown inFIG. 11, the trenches 1206 extend along an Y-axis (direction) 124 thatcrosses an X-axis (direction) 122 at an angle. In one embodiment,direction 124 is substantially perpendicular to direction 124. In oneembodiment, patterned hard mask layer 1202 is a carbon hard mask layer,a metal oxide hard mask layer, a metal nitride hard mask layer, asilicon nitride hard mask layer, a silicon oxide hard mask layer, acarbide hard mask layer, or other hard mask layer known to one ofordinary skill in the art of microelectronic device manufacturing. Inone embodiment, the patterned hard mask layer 1202 is formed using oneor more hard mask patterning techniques known to one of ordinary skillin the art of microelectronic device manufacturing. In one embodiment,the insulating layer 1102 is etched through a patterned hard mask layerto form trenches 1206 using one or more of etching techniques known toone of ordinary skill in the art of microelectronic devicemanufacturing. In one embodiment, the size of trenches in the insulatinglayer 1102 is determined by the size of conductive lines formed later onin a process.

FIG. 13A is a view 1300 similar to FIG. 12, after a mask layer 1302 isdeposited on an insulating layer 1304 on a patterned hard mask layer1202 according to one embodiment. FIG. 13B is a cross-sectional view1310 of FIG. 13A along an axis C-C′.

As shown in FIGS. 13A and 13B, an opening 1306 is formed in mask layer1202. Opening 1306 is formed above one of the conductive lines 202, asshown in FIGS. 13A and 13B. In one embodiment, the opening 1306 definesa trench portion of the fully self-aligned via formed later on in aprocess.

In one embodiment, mask layer 1302 includes a photoresist layer. In oneembodiment, mask layer 1302 includes one or more hard mask layers. Inone embodiment, the insulating layer 1304 is a hard mask layer. In oneembodiment, insulating layer 1304 includes a bottom anti-reflectivecoating (BARC) layer. In one embodiment, insulating layer 1304 includesa titanium nitride (TiN) layer, a tungsten carbide (WC) layer, atungsten bromide carbide (WBC) layer, a carbon hard mask layer, a metaloxide hard mask layer, a metal nitride hard mask layer, a siliconnitride hard mask layer, a silicon oxide hard mask layer, a carbide hardmask layer, other hard mask layer, or any combination thereof. In oneembodiment, insulating layer 1304 represents one of the insulatinglayers described above. In one embodiment, mask layer 1302 is depositedusing one or more mask layer deposition techniques known to one ofordinary skill in the art of microelectronic device manufacturing. Inone embodiment, insulating layer 1304 is deposited using one ofdeposition techniques, such as but not limited to a CVD, PVD, MBE,NOCVD, spin-on, or other insulating layer deposition techniques known toone of ordinary skill in the art of microelectronic devicemanufacturing. In one embodiment, the opening 1306 is formed using oneor more of the patterning and etching techniques known to one ofordinary skill in the art of microelectronic device manufacturing.

FIG. 14A is a view 1400 similar to FIG. 13B after the insulating layer1304 and hard mask layer 1202 are selectively etched through opening1306 to form an opening 1402 according to one embodiment. FIG. 14B is aview 1410 similar to FIG. 13A after the insulating layer 1304 andinsulating layer 1102 are selectively etched through opening 1306 toform opening 1402 according to one embodiment.

FIG. 14B is different from FIG. 13A in that FIG. 14B shows a cut throughopening 1402 along X-axis 122 and Y-axis 124. As shown in FIGS. 14A and14B, opening 1402 includes a via portion 1404 and a trench portion 1406.As shown in FIGS. 14A and 14B, via portion 1404 of the opening 1402 islimited along Y-axis 124 by insulating layer 802. Via portion 1404 ofthe opening 1402 is self-aligned along Y-axis 124 to one of theconductive lines 202. As shown in FIGS. 14A and 14B, trench portion 1406is limited along X-axis 122 by the features of the hard mask layer 1202that extend along Y-axis 124. In one embodiment, insulating layer 1102is selectively etched relative to the insulating layer 802 to formopening 1402.

In one embodiment, hard mask layer 1202 is selectively etched relativeto the insulating layer 802 to form opening 1402. As shown in FIGS. 14Aand 14B, mask layer 1302 and insulating layer 1304 are removed. In oneembodiment, mask layer 1302 is removed using one or more of the masklayer removal techniques known to one of ordinary skill in the art ofmicroelectronic device manufacturing. In one embodiment, insulatinglayer 1304 is removed using one or more of the etching techniques knownto one of ordinary skill in the art of microelectronic devicemanufacturing.

FIG. 15A is a view 1500 similar to FIG. 11, after a mask layer 1502 isdeposited on the exposed insulating layer 802 and insulating layer 1102according to one embodiment. FIG. 15B is a top view 1510 of theelectronic device structure depicted in FIG. 15A. As shown in FIG. 15A,a portion of the insulating layer 1102 is removed to even out topportions of the insulating layer 802 with top portions of the insulatinglayer 1102. As shown in FIGS. 15A and 15B, mask layer 1502 has anopening 1506 to expose hard mask layer 1502.

In one embodiment, the portion of the insulating layer 1102 is removedusing a CMP technique known to one of ordinary skill in the art ofmicroelectronic device manufacturing. In one embodiment, a portion ofthe insulating layer 1102 is etched back to expose the top portion ofthe insulating layer 802. In another embodiment, a portion of theinsulating layer 802 is etched back to a predetermined depth to exposeupper portions of the sidewalls and top portions of the insulating layer1102 in the trenches 902. In one embodiment, the portion of theinsulating layer 802 is etched back using one or more of the dry and wetetching techniques known to one of ordinary skill in the art ofmicroelectronic device manufacturing.

In one embodiment, mask layer 1502 includes a photoresist layer. In oneembodiment, mask layer 1502 includes one or more hard mask layers. Inone embodiment, mask layer 1502 is a tri-layer mask stack, e.g., a 193nm immersion (193 i) or EUV resist mask on a middle layer (ML) (e.g., asilicon containing organic layer or a metal containing dielectric layer)on a bottom anti-reflective coating (BARC) layer on a silicon oxide hardmask. In one embodiment, the hard mask layer 1504 is a metallizationlayer hard mask to pattern the conductive lines of the nextmetallization layer. In one embodiment, hard mask layer 1504 includes atitanium nitride (TiN) layer, a tungsten carbide (WC) layer, a tungstenbromide carbide (WBC) layer, a carbon hard mask layer, a metal oxidehard mask layer, a metal nitride hard mask layer, a silicon nitride hardmask layer, a silicon oxide hard mask layer, a carbide hard mask layer,other hard mask layer or any combination thereof. In one embodiment,hard mask layer 1504 represents one of the hard mask layers describedabove.

In one embodiment, the insulating layer 802 and the insulating layer1102 are patterned and etched using hard mask 1504 to form trenchesusing one or more patterning and etching techniques known to one orordinary skill in the art of microelectronic device manufacturing. Inone embodiment, the size of trenches in the insulating layer 802 andinsulating layer 1102 is determined by the size of conductive linesformed later on in a process.

In one embodiment, the mask layer 1502 is deposited using one or more ofthe mask deposition techniques known to one of ordinary skill in the artof microelectronic device manufacturing. In one embodiment, hard masklayer 1504 is deposited using one or more hard mask layer depositiontechniques, such as but not limited to a CVD, PVD, MBE, MOCVD, spin-on,or other hard mask deposition known to one of ordinary skill in the artof microelectronic device manufacturing. In one embodiment, the opening1506 is formed using one or more of the patterning and etchingtechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing.

FIG. 16A is a view 1600 similar to FIG. 15A, after portions of the hardmask layer 1504, insulating layer 802 and insulating layer 1102 areremoved through opening 1506 to form an opening 1602 in insulating layer802 according to one embodiment. FIG. 16B is a top view 1620 of theelectronic device structure depicted in FIG. 16A. In one embodiment,opening 1602 is a trench opening for a via. As shown in FIGS. 16A and16B, opening 1602 includes a bottom 1612 that includes a portion 1604 ofthe insulating layer 1102 between portions 1606 and 1608 of theinsulating layer 802. As shown in FIGS. 16A and 16B, opening 1602includes opposing sidewalls 1610 that include portions of the insulatinglayer 802. In one embodiment, each sidewall 1610 is substantiallyorthogonal to bottom 1612. In another embodiment, each sidewall 1610 isslanted relative to bottom 1612 at an angle other than 90 degrees, sothat an upper portion of the opening 1602 is greater than a lowerportion of the opening 1602.

In one embodiment, opening 1602 having slanted sidewalls is formed usingan angled non-selective etch. In one embodiment, hard mask layer 1504 isremoved using one or more of wet etching, dry etching, or a combinationthereof techniques known to one of ordinary skill in the art ofmicroelectronic device manufacturing. In one embodiment, insulatinglayer 802 and insulating layer 1102 are removed using a non-selectiveetch in a trench first dual damascene process. In one embodiment,insulating layer 802 and insulating layer 1102 are etched down to thedepth that is determined by time. In another embodiment, insulatinglayer 802 and insulating layer 1102 are etched non-selectively down toan etch stop layer (not shown). In one embodiment, insulating layer 802and insulating layer 1102 are non-selectively etched using one or moreof wet etching, dry etching, or a combination thereof techniques knownto one of ordinary skill in the art of electronic device manufacturing.

FIG. 17A is a view 1700 similar to FIG. 16A, after a fully self-alignedopening 1702 is formed in insulating layer 802 according to oneembodiment. FIG. 17B is a top view 1720 of the electronic devicestructure depicted in FIG. 17A. As shown in FIGS. 17A and 17B, masklayer 1502 is removed. Mask layer 1502 can be removed using one of themask layer removal techniques known to one of ordinary skill in the artof microelectronic device manufacturing. A patterned mask layer 1714 isformed on hard mask layer 1504. As shown in FIG. 17B, patterned masklayer 1714 is deposited on the hard mask layer 1504 and into opening1602. Patterned mask layer 1714 has an opening 1708. Patterned masklayer 1714 can be formed using one or more of the mask layer depositing,patterning and etching techniques known to one of ordinary skill in theart of microelectronic device manufacturing.

Fully self-aligned opening 1702 is formed through mask opening 1708.Fully self-aligned opening 1702 includes a trench opening 1706 and a viaopening 1704, as shown in FIGS. 17A and 17B. Via opening 1704 isunderneath trench opening 1706. In one embodiment, trench opening 1706is the part of that is exposed through opening 1708.

In one embodiment, via opening 1704 is formed by selectively etchinginsulating layer 1102 relative to the insulating layer 802 through maskopening 1708 and trench opening 1706. In one embodiment, trench opening1706 extends along Y-axis 124. As shown in FIG. 17B, trench opening 1706is greater along Y-axis 124 than along X-axis 122.

In one embodiment, trench opening 1706 of the opening 1702 isself-aligned along X-cross-sectional axis 122 between the features ofthe hard mask layer 1504 that are used to pattern the uppermetallization layer conductive lines that extend along Y-axis 124 (notshown). The via opening 1704 of the opening 1702 is self-aligned alongY-axis 124 by the insulating layer 802 that is left intact byselectively etching the portion 1604 of the insulating layer 1102relative to the insulating layer 802. This provides an advantage as thesize of the trench opening 1706 does not need to be limited to the sizeof the cross-section between the conductive line 1716 and one of theconductive lines of the upper metallization layer that provides moreflexibility for the lithography equipment. As the portion 1604 isselectively removed relative to the insulating layer 802, the size ofthe trench opening increases.

As shown in FIGS. 16A and 16B, the portion 1604 is self-aligned with aconductive line 1716 that is one of the lower metallization layerconductive lines 202. That is, the opening 1702 is self-aligned alongboth X and Y axes.

FIG. 17A is different from FIG. 16A in that FIG. 17A illustrates trenchopening 1706 having slanted sidewalls 1710. Each sidewall 1710 is at anangle other than 90 degrees to the top surface of the substrate 102, sothat an upper portion of the trench opening 1706 is greater than a lowerportion of the trench opening 1706. In another embodiment, the sidewalls1710 are substantially orthogonal to the top surface of the substrate102.

In one embodiment, mask layer 1714 includes a photoresist layer. In oneembodiment, mask layer 1714 includes one or more hard mask layers. Inone embodiment, mask layer 1714 is tri-layer mask stack, e.g., a 193 ior EUV resist mask on a ML (e.g., a silicon containing organic layer ora metal containing dielectric layer) on a BARC layer on a silicon oxidehard mask. As shown in FIGS. 17A and 17B, via opening 1704 exposes aportion 1712 of the liner 302 on conductive line 1716. In anotherembodiment, when the liner 302 is removed, the via opening 1704 exposesconductive line 1716.

FIG. 18A is a view 1800 similar to FIG. 17A, after an uppermetallization layer My comprising conductive lines extending alongY-axis 124 is formed according to one embodiment. FIG. 18B is a top view1830 of the electronic device structure depicted in FIG. 18A. FIG. 18Ais a cross-sectional view of FIG. 18B along an axis D-D′. As shown inFIG. 18A, mask layer 1502 and hard mask layer 1504 are removed. In oneembodiment, each of the mask layer 1502 and hard mask layer 1504 isremoved using one or more of the hard mask layer removal techniques knowin one of ordinary skill in the art of microelectronic devicemanufacturing.

An upper metallization layer My includes a set of conductive lines 1802that extend on portions of insulating layer 1102 and portions insulatinglayer 802. As shown in FIG. 18B, the portions of the insulating layer1102 are between the portions of the insulating layer 802. Conductivelines 1802 extend along Y-axis 124. A fully self-aligned via 1824includes a trench portion 1804 and a via portion 1806. Via portion 1806is underneath trench portion 1804. The fully self-aligned via 1824 isbetween the lower metallization layer comprising conductive lines 202that extend along X-axis 122 and the upper metallization layercomprising conductive lines 1802. As shown in FIGS. 18A and 18B, the viaportion 1806 is on liner 302 on conductive line 1716. As shown in FIGS.18A and 18B, the via portion 1806 of the via 1824 is self-aligned alongthe Y-axis 124 to conductive line 1716 that is one of the conductivelines 202. The via portion 1806 of the via 1824 is self-aligned alongthe X-axis (direction) 122 to a conductive line 1822 that is one of theconductive lines 1802. In one embodiment, when liner 302 is removed, thevia portion 1806 is directly on conductive line 1716. As shown in FIGS.18A and 18B, the via portion 1806 is a part of the conductive line 1822.As shown in FIGS. 18A and 18B, the size of the via portion 1806 isdetermined by the size of the cross-section between the conductive line1716 and conductive line 1822.

In one embodiment, forming the conductive lines 1802 and via 1824involves filling the trenches in the insulating layer and the opening1702 with a layer of conductive material. In one embodiment, a baselayer (not shown) is first deposited on the internal sidewalls andbottom of the trenches and the opening 1702, and then the conductivelayer is deposited on the base layer. In one embodiment, the base layerincludes a conductive seed layer (not shown) deposited on a conductivebarrier layer (not shown). The seed layer can include copper, and theconductive barrier layer can include aluminum, titanium, tantalum,tantalum nitride, and the like metals. The conductive barrier layer canbe used to prevent diffusion of the conductive material from the seedlayer, e.g., copper, into the insulating layer. Additionally, theconductive barrier layer can be used to provide adhesion for the seedlayer (e.g., copper).

In one embodiment, to form the base layer, the conductive barrier layeris deposited onto the sidewalls and bottom of the trenches, and then theseed layer is deposited on the conductive barrier layer. In anotherembodiment, the conductive base layer includes the seed layer that isdirectly deposited onto the sidewalls and bottom of the trenches. Eachof the conductive barrier layer and seed layer may be deposited usingany thin film deposition technique known to one of ordinary skill in theart of semiconductor manufacturing, e.g., sputtering, blanketdeposition, and the like. In one embodiment, each of the conductivebarrier layer and the seed layer has the thickness in an approximaterange from about 1 nm to about 100 nm. In one embodiment, the barrierlayer may be a thin dielectric that has been etched to establishconductivity to the metal layer below. In one embodiment, the barrierlayer may be omitted altogether and appropriate doping of the copperline may be used to make a “self-forming barrier”.

In one embodiment, the conductive layer e.g., copper or cobalt, isdeposited onto the seed layer of base later of copper, by anelectroplating process. In one embodiment, the conductive layer isdeposited into the trenches using a damascene process known to one ofordinary skill in the art of microelectronic device manufacturing. Inone embodiment, the conductive layer is deposited onto the seed layer inthe trenches and in the opening 1702 using a selective depositiontechnique, such as but not limited to electroplating, electrolysis, aCVD, PVD, MBE, MOCVD, ALD, spin-on, or other deposition techniques knownto one of ordinary skill in the art of microelectronic devicemanufacturing.

In one embodiment, the choice of a material for conductive layer for theconductive lines 1802 and via 1824 determines the choice of a materialfor the seed layer. For example, if the material for the conductivelines 1802 and via 1824 includes copper, the material for the seed layeralso includes copper. In one embodiment, the conductive lines 1802 andvia 1824 include a metal, for example, copper (Cu), ruthenium (Ru),nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn),titanium (Ti), aluminum (Al), hafnium (Hf), tantalum (Ta), tungsten (W),vanadium (V), molybdenum (Mo), palladium (Pd), gold (Au), silver (Ag),platinum (Pt), indium (In), tin (Sn), lead (Pb), antimony (Sb), bismuth(Bi), zinc (Zn), cadmium (Cd), or any combination thereof.

In alternative embodiments, examples of the conductive materials thatmay be used for the conductive lines 1802 and via 1824 include metals,e.g., copper, tantalum, tungsten, ruthenium, titanium, hafnium,zirconium, aluminum, silver, tin, lead, metal alloys, metal carbides,e.g., hafnium carbide, zirconium carbide, titanium carbide, tantalumcarbide, aluminum carbide, other conductive materials, or anycombination thereof.

In one embodiment, portions of the conductive layer and the base layerare removed to even out top portions of the conductive lines 1802 withtop portions of the insulating layer 802 and insulating layer 1102 usinga chemical-mechanical polishing (“CMP”) technique known to one ofordinary skill in the art of microelectronic device manufacturing.

In one non-limiting example, the thickness of the conductive lines 1802is in an approximate range from about 15 nm to about 1000 nm. In onenon-limiting example, the thickness of the conductive lines 1802 is fromabout 20 nm to about 200 nm. In one non-limiting example, the width ofthe conductive lines 1802 is in an approximate range from about 5 nm toabout 500 nm. In one non-limiting example, the spacing (pitch) betweenthe conductive lines 1802 is from about 2 nm to about 500 nm. In morespecific non-limiting example, the spacing (pitch) between theconductive lines 1802 is from about 5 nm to about 50 nm.

FIGS. 19 through 23 (including both A and B designations) illustrateanother embodiment of the disclosure. FIG. 19A is a view 1900 similar toFIG. 11, after a mask layer 1904 is deposited on a hard mask layer 1902on the insulating layer 1102 according to one embodiment. FIG. 19B is atop view 1910 of the electronic device structure depicted in FIG. 19A.As shown in FIGS. 19A and 19B, mask layer 1904 has an opening 1906 toexpose hard mask layer 1902.

In one embodiment, mask layer 1904 includes a photoresist layer. In oneembodiment, mask layer 1904 includes one or more hard mask layers. Inone embodiment, mask layer 1904 is a tri-layer mask stack, e.g., a 193nm immersion (193 i) or EUV resist mask on a middle layer (ML) (e.g., asilicon containing organic layer or a metal containing dielectric layer)on a bottom anti-reflective coating (BARC) layer on a silicon oxide hardmask. In one embodiment, the hard mask layer 1902 is a metallizationlayer hard mask to pattern the conductive lines of the nextmetallization layer. In one embodiment, hard mask layer 1902 includes atitanium nitride (TiN) layer, a tungsten carbide (WC) layer, a tungstenbromide carbide (WBC) layer, a carbon hard mask layer, a metal oxidehard mask layer, a metal nitride hard mask layer, a silicon nitride hardmask layer, a silicon oxide hard mask layer, a carbide hard mask layer,other hard mask layer or any combination thereof. In one embodiment,hard mask layer 1804 represents one of the hard mask layers describedabove.

In one embodiment, the mask layer 1904 is deposited using one or more ofthe mask deposition techniques known to one of ordinary skill in the artof microelectronic device manufacturing. In one embodiment, hard masklayer 1902 is deposited using one or more hard mask layer depositiontechniques, such as but not limited to a CVD, PVD, MBE, MOCVD, spin-on,or other hard mask deposition known to one of ordinary skill in the artof microelectronic device manufacturing. In one embodiment, the opening1906 is formed using one or more of the patterning and etchingtechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing.

FIG. 20A is a view 2000 similar to FIG. 19A, after portions of the hardmask layer 1902 and insulating layer 1102 are removed through opening1906 to form an opening 2002 in insulating layer 1102 according to oneembodiment. FIG. 20B is a top view 2050 of the electronic devicestructure depicted in FIG. 20A. In one embodiment, opening 2002 is atrench opening for a via. As shown in FIGS. 20A and 20B, opening 2002includes a bottom 2010 that includes a portion 2004 of the insulatinglayer 1102 between portions 2006 and 2008 of the insulating layer 802.As shown in FIGS. 20A and 20B, opening 2002 includes opposing sidewalls2012 that include portions of the insulating layer 1102. In oneembodiment, each sidewall 2012 is substantially orthogonal to bottom2010. In another embodiment, each sidewall 2012 is slanted relative tobottom 2010 at an angle other than 90 degrees, so that an upper portionof the opening 2002 is greater than a lower portion of the opening 2002.

In one embodiment, opening 2002 having slanted sidewalls is formed usingan angled non-selective etch. In one embodiment, hard mask layer 1902 isremoved using one or more of wet etching, dry etching, or a combinationthereof techniques known to one of ordinary skill in the art ofmicroelectronic device manufacturing. In one embodiment, insulatinglayer 1102 is removed using a non-selective etch in a trench first dualdamascene process. In one embodiment, insulating layer 1102 is etcheddown to the depth that is determined by time. In another embodiment,insulating layer 1102 is etched non-selectively down to an etch stoplayer (not shown). In one embodiment, insulating layer 1102 isnon-selectively etched using one or more of wet etching, dry etching, ora combination thereof techniques known to one of ordinary skill in theart of electronic device manufacturing.

FIG. 21A is a view 2100 similar to FIG. 20A, after mask layer 1904 isremoved, planarization filling layer 2102 is formed and mask layer 2104with a fully self-aligned opening 2106 is formed according to oneembodiment. FIG. 21B is a top view 2110 of the electronic devicestructure depicted in FIG. 21A. As shown in FIGS. 21A and 21B, masklayer 1904 is removed. Mask layer 1904 can be removed using one of themask layer removal techniques known to one of ordinary skill in the artof microelectronic device manufacturing. A planarization filling layer2102 is formed in opening 2002 onto the tops of exposed insulating layer802 and insulating layer 1102. The planarization filling layer 2102illustrated is formed so that an overburden 2108 is formed on hard mask1902. In some embodiments, the planarization filling layer 2102 isformed to be substantially coplanar with the hard mask 1902. In someembodiments, the planarization filling layer 2102 is planarized, forexample, by a CMP process. The planarization filling layer 2102 can beany suitable material including, but not limited to, BARC (BottomAnti-Reflective Coating) layer (e.g., spin-on polymers containing C andH, or Si), DARC (Dielectric Anti-Reflective Coating) layer or an OPL(Organic Planarization Layer). The planarization filling layer 2102 ofsome embodiments is deposited by CVD or ALD. In some embodiments, theplanarization filling layer 2102 comprises one or more atoms of Si, O,N, C or H.

A patterned mask layer 2104 is formed on hard mask layer 1902. As shownin FIG. 21B, patterned mask layer 2104 is deposited on the planarizationfilling layer 2102. Patterned mask layer 2104 has an opening 2106.Patterned mask layer 2104 can be formed using one or more of the masklayer depositing, patterning and etching techniques known to one ofordinary skill in the art of microelectronic device manufacturing.

In one embodiment, mask layer 2104 includes a photoresist layer. In oneembodiment, mask layer 2104 includes one or more hard mask layers. Inone embodiment, mask layer 2104 is tri-layer mask stack, e.g., a 193 ior EUV resist mask on a ML (e.g., a silicon containing organic layer ora metal containing dielectric layer) on a BARC layer on a silicon oxidehard mask.

FIG. 22A is a view 2200 similar to FIG. 21A, after removing theplanarization filling layer 2102 and insulating layer 1102 throughopening 2106. The embodiment illustrated has the patterned hard masklayer 2104 and planarization filling layer 2102 removed from hard mask1902. A fully self-aligned opening 2202 is formed through mask opening2106. Fully self-aligned opening 2202 includes a trench opening 2206 anda via opening 2204, as shown in FIGS. 22A and 22B. Via opening 2204 isunderneath trench opening 2206.

In one or more embodiments, via opening 2204 is formed by selectivelyetching insulating layer 1102 relative to the insulating layer 802through mask opening 2106 and trench opening 2206. In one embodiment,trench opening 2206 extends along Y-axis 124. As shown in FIG. 22B,trench opening 2206 is greater along Y-axis 124 than along X-axis 122.

In one embodiment, trench opening 2206 of the opening 2202 isself-aligned along X-axis between the features of the hard mask layer1902 that are used to pattern the upper metallization layer conductivelines that extend along Y-axis 124 (not shown). The via opening 2204 ofthe opening 2202 is self-aligned along Y-axis 124 by the insulatinglayer 802 that is left intact by selectively etching the portion 2004 ofthe insulating layer 1102 relative to the insulating layer 802. Thisprovides an advantage as the size of the trench opening 2206 does notneed to be limited to the size of the cross-section between theconductive line 2216 and one of the conductive lines of the uppermetallization layer that provides more flexibility for the lithographyequipment. As the portion 2004 is selectively removed relative to theinsulating layer 802, the size of the trench opening increases.

As shown in FIGS. 20A and 20B, the portion 2004 is self-aligned with aconductive line 2216 that is one of the lower metallization layerconductive lines 202. That is, the opening 2202 is self-aligned alongboth X and Y axes.

FIG. 22A illustrates trench opening 2206 having sidewalls 2210 that aresubstantially orthogonal to the top surface of the substrate 102. Insome embodiments, each sidewall 2210 is at an angle other than 90degrees to the top surface of the substrate 102, so that an upperportion of the trench opening 2206 is greater than a lower portion ofthe trench opening 2206.

As shown in FIGS. 22A and 22B, via opening 2204 exposes a portion 2212of the liner 302 on conductive line 2216. In another embodiment, whenthe liner 302 is removed, the via opening 2204 exposes conductive line2216.

FIG. 23A is a view 2300 similar to FIG. 22A, after an uppermetallization layer My comprising conductive lines extending alongY-axis 124 is formed according to one embodiment. FIG. 23B is a top view2330 of the electronic device structure depicted in FIG. 23A. FIG. 23Ais a cross-sectional view of FIG. 23B taken along an axis D-D′. As shownin FIG. 23A, hard mask layer 1902 is removed. In one embodiment, hardmask layer 1902 is removed using one or more of the hard mask layerremoval techniques know in one of ordinary skill in the art ofmicroelectronic device manufacturing.

An upper metallization layer My includes a set of conductive lines 2302that extend on portions of insulating layer 802. In the embodimentillustrated in FIG. 23A, the conductive lines 2302 are filled to beco-planar with the top of insulating layer 1102. In some embodiments,the conductive lines 2302 extend above the top surface of insulatinglayer 1102, similar to that shown in FIG. 18A.

As shown in FIG. 23B, the portions of the insulating layer 1102 arebetween the portions of the insulating layer 802. Conductive lines 2302extend along Y-axis 124. A fully self-aligned via 2324 includes a trenchportion 2304 and a via portion 2306. Via portion 2306 is underneathtrench portion 2304. The fully self-aligned via 2324 is between thelower metallization layer comprising conductive lines 202 that extendalong X-axis 122 and the upper metallization layer comprising conductivelines 2302. As shown in FIGS. 23A and 23B, the via portion 2306 is onliner 302 on conductive line 2216. As shown in FIGS. 23A and 23B, thevia portion 2306 of the via 2324 is self-aligned along the Y-axis 124 toconductive line 2216 that is one of the conductive lines 202. The trenchportion 2306 of the via 2324 is self-aligned along the X-axis 122. Inone embodiment, when liner 302 is removed, the via portion 2306 isdirectly on conductive line 2216.

In one embodiment, forming the conductive lines 2302 and via 2324involves filling the trenches in the insulating layer and the opening2202 with a layer of conductive material. In one embodiment, a baselayer (not shown) is first deposited on the internal sidewalls andbottom of the trenches and the opening 2202, and then the conductivelayer is deposited on the base layer. In one embodiment, the base layerincludes a conductive seed layer (not shown) deposited on a conductivebarrier layer (not shown). The seed layer can include copper, and theconductive barrier layer can include aluminum, titanium, tantalum,tantalum nitride, and the like metals. The conductive barrier layer canbe used to prevent diffusion of the conductive material from the seedlayer, e.g., copper, into the insulating layer. Additionally, theconductive barrier layer can be used to provide adhesion for the seedlayer (e.g., copper or cobalt).

In one embodiment, to form the base layer, the conductive barrier layeris deposited onto the sidewalls and bottom of the trenches, and then theseed layer is deposited on the conductive barrier layer. In anotherembodiment, the conductive base layer includes the seed layer that isdirectly deposited onto the sidewalls and bottom of the trenches. Eachof the conductive barrier layer and seed layer may be deposited usingany thin film deposition technique known to one of ordinary skill in theart of semiconductor manufacturing, e.g., sputtering, blanketdeposition, and the like. In one embodiment, each of the conductivebarrier layer and the seed layer has the thickness in an approximaterange from about 1 nm to about 100 nm. In one embodiment, the barrierlayer may be a thin dielectric that has been etched to establishconductivity to the metal layer below. In one embodiment, the barrierlayer may be omitted altogether and appropriate doping of the copperline may be used to make a “self-forming barrier”.

In one embodiment, the conductive layer e.g., copper, is deposited ontothe seed layer of base later of copper, by an electroplating process. Inone embodiment, the conductive layer is deposited into the trenchesusing a damascene process known to one of ordinary skill in the art ofmicroelectronic device manufacturing. In one embodiment, the conductivelayer is deposited onto the seed layer in the trenches and in theopening 2202 using a selective deposition technique, such as but notlimited to electroplating, electrolysis, a CVD, PVD, MBE, MOCVD, ALD,spin-on, or other deposition techniques known to one of ordinary skillin the art of microelectronic device manufacturing.

In one embodiment, the choice of a material for conductive layer for theconductive lines 2302 and via 2324 determines the choice of a materialfor the seed layer. For example, if the material for the conductivelines 2302 and via 2324 includes copper, the material for the seed layeralso includes copper. In one embodiment, the conductive lines 2302 andvia 2324 include a metal, for example, copper (Cu), ruthenium (Ru),nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn),titanium (Ti), aluminum (Al), hafnium (Hf), tantalum (Ta), tungsten (W),vanadium (V), molybdenum (Mo), palladium (Pd), gold (Au), silver (Ag),platinum (Pt), indium (In), tin (Sn), lead (Pb), antimony (Sb), bismuth(Bi), zinc (Zn), cadmium (Cd), or any combination thereof.

In alternative embodiments, examples of the conductive materials thatmay be used for the conductive lines 2302 and via 2324 are, but notlimited to, metals, e.g., copper, tantalum, tungsten, ruthenium,titanium, hafnium, zirconium, aluminum, silver, tin, lead, metal alloys,metal carbides, e.g., hafnium carbide, zirconium carbide, titaniumcarbide, tantalum carbide, aluminum carbide, other conductive materials,or any combination thereof.

In one embodiment, portions of the conductive layer and the base layerare removed to even out top portions of the conductive lines 2302 withtop portions of the insulating layer 1102 using a chemical-mechanicalpolishing (“CMP”) technique known to one of ordinary skill in the art ofmicroelectronic device manufacturing.

In one non-limiting example, the thickness of the conductive lines 2302is in an approximate range from about 15 nm to about 1000 nm. In onenon-limiting example, the thickness of the conductive lines 2302 is fromabout 20 nm to about 200 nm. In one non-limiting example, the width ofthe conductive lines 2302 is in an approximate range from about 5 nm toabout 500 nm. In one non-limiting example, the spacing (pitch) betweenthe conductive lines 2302 is from about 2 nm to about 500 nm. In morespecific non-limiting example, the spacing (pitch) between theconductive lines 2302 is from about 5 nm to about 50 nm.

In an embodiment, the upper metallization layer My is configured toconnect to other metallization layers (not shown). In an embodiment, themetallization layer My is configures to provide electrical contact toelectronic devices, e.g., transistors, memories, capacitors, resistors,optoelectronic devices, switches, and any other active and passiveelectronic devices that are separated by an electrically insulatinglayer, for example, an interlayer dielectric, a trench insulation layer,or any other insulating layer known to one or ordinary skill in the artof electronic device manufacturing.

FIG. 24 shows a block diagram of a plasma system to perform at leastsome of the operations to provide a fully self-aligned via according toone embodiment. As shown in FIG. 24, system 2400 has a processingchamber 2402. A movable pedestal 2404 to hold an electronic devicestructure 2406 is placed in processing chamber 2402. Pedestal 2404comprises an electrostatic chuck (“ESC”), a DC electrode embedded intothe ESC, and a cooling/heating base. In an embodiment, pedestal 2404acts as moving cathode. In an embodiment, the ESC comprises an Al₂O₃material, Y₂O₃ or other ceramic materials known to one of ordinary skillof electronic device manufacturing. A DC power supply 2408 is connectedto the DC electrode of the pedestal 2404.

As shown in FIG. 24, an electronic device structure 2406 is loadedthrough an opening 2416 and placed on the pedestal 2404. The electronicdevice structure 2406 represents one of the electronic device structuresdescribed above. System 2400 comprises an inlet to input one or moreprocess gases 2424 through a mass flow controller 2422 to a plasmasource 2426. A plasma source 2426 comprising a showerhead 2428 iscoupled to the processing chamber 2402 to receive one or more gases 2424to generate plasma. Plasma source 2416 is coupled to a RF source power2420. Plasma source 2426 through showerhead 2428 generates a plasma 2430in processing chamber 2402 from one or more process gases 2424 using ahigh frequency electric field. Plasma 2430 comprises plasma particles,such as ions, electrons, radicals, or any combination thereof. In anembodiment, power source 2410 supplies power from about 50 W to about3000 W at a frequency from about 400 kHz to about 162 MHz to generateplasma 2430.

A plasma bias power 2410 is coupled to the pedestal 2404 (e.g., cathode)via a RF match 2414 to energize the plasma. In an embodiment, the plasmabias power 2410 provides a bias power that is not greater than 1000 W ata frequency between about 2 MHz to 60 MHz, and in a particularembodiment at about 13 MHz. A plasma bias power 2412 may also beprovided, for example, to provide another bias power that is not greaterthan 1000 W at a frequency from about 400 kHz to about 60 MHz, and in aparticular embodiment, at about 60 MHz. Plasma bias power 2412 and biaspower 2410 are connected to RF match 2414 to provide a dual frequencybias power. In an embodiment, a total bias power applied to the pedestal2404 is from about 10 W to about 3000 W.

As shown in FIG. 24, a pressure control system 2418 provides a pressureto processing chamber 2402. As shown in FIG. 24, chamber 2402 has one ormore exhaust outlets 2432 to evacuate volatile products produced duringprocessing in the chamber. In an embodiment, the plasma system 2400 isan inductively coupled plasma (ICP) system. In an embodiment, the plasmasystem 2400 is a capacitively coupled plasma (CCP) system.

A control system 2434 is coupled to the chamber 2402. The control system2434 comprises a processor 2436, a temperature controller 2438 coupledto the processor 2436, a memory 2440 coupled to the processor 2436, andinput/output devices 2442 coupled to the processor 2436 to form fullyself-aligned via as described herein.

In one embodiment, the processor 2436 has a configuration to controlrecessing first conductive lines on a first insulating layer on asubstrate, the first conductive lines extending along a first directionon the first insulating layer. The processor 2436 has a configuration tocontrol depositing a liner on the recessed first conductive lines. Theprocessor has a configuration to control selectively growing a seedlayer on the recessed first conductive lines. The processor 2436 has aconfiguration to control forming pillars using the selectively grownseed layer. The processor 2436 has a configuration to control depositinga second insulating layer between the pillars. The processor 2436 has aconfiguration to control removing the pillars to form trenches in thesecond insulating layer. The processor 2436 has a configuration tocontrol depositing a third insulating layer into the trenches in thesecond insulating layer. The processor 2436 has a configuration tocontrol selectively etching the third insulating layer relative to thesecond insulating layer to form a fully self-aligned via opening down toone of the first conductive lines. The processor 2436 has aconfiguration to control depositing a conductive layer into theself-aligned via opening, as described above.

The control system 2434 is configured to perform at least some of themethods as described herein and may be either software or hardware or acombination of both. The plasma system 2400 may be any type of highperformance processing plasma systems known in the art, such as but notlimited to, an etcher, a cleaner, a furnace, or any other plasma systemto manufacture electronic devices.

FIG. 25A illustrates a top view 3000 and a cross-sectional view 3012 ofan electronic device structure to provide a fully self-aligned viaaccording to another embodiment. FIG. 25A is similar to FIG. 1A, afteran etch stop layer 3014 is formed on the insulating layer 3004 prior tothe formation of the cap layer 3010. The cross-sectional view 3012 isalong an axis E-E′, as depicted in FIG. 25A. FIG. 25B is a perspectiveview 3020 of the electronic device structure depicted in FIG. 25A. Alower metallization layer (Mx) comprises a set of conductive lines 3006that extend along an X-axis (direction) 122 on an insulating layer 3004on a substrate 3002, as shown in FIGS. 25A and 25B. As shown in FIG.25B, X-axis (direction) 122 crosses Y-axis (direction) 124 at an angle126. In one embodiment, angle 126 is about 90 degrees. In anotherembodiment, angle 126 is an angle that is other than the 90 degreesangle. The insulating layer 3004 comprises trenches 3008. The recessedconductive lines 3006 are deposited in trenches 3008. A cap layer 3010is formed on the insulating layer 3004.

In one embodiment, the etch stop layer 3014 is aluminum oxide (Al₂O₃).In one or more embodiment, the etch stop layer 3014 is selected fromaluminum oxide (Al₂O₃), hafnium dioxide (HfO₂), and combinationsthereof.

In an embodiment, the substrate 3002 comprises a semiconductor material,e.g., silicon (Si), carbon (C), germanium (Ge), silicon germanium(SiGe), gallium arsenide (GaAs), indium phosphide (InP), indium galliumarsenide (InGaAs), aluminum indium arsenide (InAlAs), othersemiconductor material, or any combination thereof. In an embodiment,substrate 3002 is a semiconductor-on-isolator (SOI) substrate includinga bulk lower substrate, a middle insulation layer, and a topmonocrystalline layer. The top monocrystalline layer may comprise anymaterial listed above, e.g., silicon. In various embodiments, thesubstrate 3002 can be, e.g., an organic, a ceramic, a glass, or asemiconductor substrate 3002. Although a few examples of materials fromwhich the substrate 3002 may be formed are described here, any materialthat may serve as a foundation upon which passive and active electronicdevices (e.g., transistors, memories, capacitors, inductors, resistors,switches, integrated circuits, amplifiers, optoelectronic devices, orany other electronic devices) may be built falls within the spirit andscope of the present disclosure.

In one embodiment, substrate 3002 includes one or more metallizationinterconnect layers for integrated circuits. In at least someembodiments, the substrate 3002 includes interconnects, for example,vias, configured to connect the metallization layers. In at least someembodiments, the substrate 3002 includes electronic devices, e.g.,transistors, memories, capacitors, resistors, optoelectronic devices,switches, and any other active and passive electronic devices that areseparated by an electrically insulating layer, for example, aninterlayer dielectric, a trench insulation layer, or any otherinsulating layer known to one of ordinary skill in the art of theelectronic device manufacturing. In one embodiment, the substrateincludes one or more buffer layers to accommodate for a lattice mismatchbetween the substrate 3002 and one or more layers above substrate 3002and to confine lattice dislocations and defects.

Insulating layer 3004 can be any material suitable to insulate adjacentdevices and prevent leakage. In one embodiment, electrically insulatinglayer 3004 is an oxide layer, e.g., silicon dioxide, or any otherelectrically insulating layer determined by an electronic device design.In one embodiment, insulating layer 3004 comprises an interlayerdielectric (ILD). In one embodiment, insulating layer 3004 is a low-kdielectric that includes, but is not limited to, materials such as,e.g., silicon dioxide, silicon oxide, carbon doped oxide (“CDO”), e.g.,carbon doped silicon dioxide, porous silicon dioxide (SiO₂), siliconnitride (SiN), or any combination thereof.

In one embodiment, insulating layer 3004 includes a dielectric materialhaving a k-value less than 5. In one embodiment, insulating layer 3004includes a dielectric material having a k-value less than 2. In at leastsome embodiments, insulating layer 3004 includes a nitride, oxide, apolymer, phosphosilicate glass, fluorosilicate (SiOF) glass,organosilicate glass (SiOCH), other electrically insulating layerdetermined by an electronic device design, or any combination thereof.In at least some embodiments, insulating layer 3004 may includepolyimide, epoxy, photodefinable materials, such as benzocyclobutene(BCB), and WPR-series materials, or spin-on-glass.

In one embodiment, insulating layer 3004 is a low-k interlayerdielectric to isolate one metal line from other metal lines on substrate3002. In one embodiment, the thickness of the layer 3004 is in anapproximate range from about 10 nanometers (nm) to about 2 microns (μm).

In an embodiment, insulating layer 3004 is deposited using one ofdeposition techniques, such as but not limited to a chemical vapordeposition (“CVD”), a physical vapor deposition (“PVD”), molecular beamepitaxy (“MBE”), metalorganic chemical vapor deposition (“MOCVD”),atomic layer deposition (“ALD”), spin-on, or other insulating depositiontechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing.

In one embodiment, the lower metallization layer Mx comprisingconductive lines 3006 (i.e., metal lines) is a part of a back endmetallization of the electronic device. In one embodiment, theinsulating layer 3004 is patterned and etched using a hard mask to formtrenches 3008 using one or more patterning and etching techniques knownto one of ordinary skill in the art of microelectronic devicemanufacturing. In one embodiment, the size of trenches 3008 in theinsulating layer 3004 is determined by the size of conductive linesformed later on in a process.

In one embodiment, forming the conductive lines 3006 involves fillingthe trenches 3008 with a layer of conductive material. In oneembodiment, a base layer (not shown) is first deposited on the internalsidewalls and bottom of the trenches 3008, and then the conductive layeris deposited on the base layer. In one embodiment, the base layerincludes a conductive seed layer (not shown) deposited on a conductivebarrier layer (not shown). The seed layer can include copper (Cu), andthe conductive barrier layer can include aluminum (Al), titanium (Ti),tantalum (Ta), tantalum nitride (TaN), and the like metals. Theconductive barrier layer can be used to prevent diffusion of theconductive material from the seed layer, e.g., copper or cobalt, intothe insulating layer 3004. Additionally, the conductive barrier layercan be used to provide adhesion for the seed layer (e.g., copper).

In one embodiment, to form the base layer, the conductive barrier layeris deposited onto the sidewalls and bottom of the trenches 3008, andthen the seed layer is deposited on the conductive barrier layer. Inanother embodiment, the conductive base layer includes the seed layerthat is directly deposited onto the sidewalls and bottom of the trenches3008. Each of the conductive barrier layer and seed layer may bedeposited using any think film deposition technique known to one ofordinary skill in the art of semiconductor manufacturing, e.g.,sputtering, blanket deposition, and the like. In one embodiment, each ofthe conductive barrier layer and the seed layer has the thickness in anapproximate range from about 1 nm to about 100 nm. In one embodiment,the barrier layer may be a thin dielectric that has been etched toestablish conductivity to the metal layer below. In one embodiment, thebarrier layer may be omitted altogether and appropriate doping of thecopper line may be used to make a “self-forming barrier”.

In one embodiment, the conductive layer e.g., copper or cobalt, isdeposited onto the seed layer of base layer of copper, by anelectroplating process. In one embodiment, the conductive layer isdeposited into the trenches 3008 using a damascene process known to oneof ordinary skill in the art of microelectronic device manufacturing. Inone embodiment, the conductive layer is deposited onto the seed layer inthe trenches 3008 using a selective deposition technique, such as butnot limited to electroplating, electrolysis, CVD, PVD, MBE, MOCVD, ALD,spin-on, or other deposition techniques know to one of ordinary skill inthe art of microelectronic device manufacturing.

In one embodiment, the choice of a material for conductive layer for theconductive lines 3006 determines the choice of a material for the seedlayer. For example, if the material for the conductive lines 3006includes copper, the material for the seed layer also includes copper.In one embodiment, the conductive lines 3006 include a metal, forexample, copper (Cu), ruthenium (Ru), nickel (Ni), cobalt (Co), chromium(Cr), iron (Fe), manganese (Mn), titanium (Ti), aluminum (Al), hafnium(Hf), tantalum (Ta), tungsten (W), vanadium (V), molybdenum (Mo),palladium (Pd), gold (Au), silver (Ag), platinum (Pt), indium (In), tin(Sn), lead (Pd), antimony (Sb), bismuth (Bi), zinc (Zn), cadmium (Cd),or any combination thereof.

In alternative embodiments, examples of the conductive materials thatmay be used for the conductive lines 3006 of the metallization layer Mxare, but not limited to, metals, e.g., copper (Cu), tantalum (Ta),tungsten (W), ruthenium (Ru), titanium (Ti), hafnium (Hf), zirconium(Zr), aluminum (Al), silver (Ag), tin (Sn), lead Pb), metal alloys,metal carbides, e.g., hafnium carbide (HfC), zirconium carbide (ZrC),titanium carbide (TiC), tantalum carbide (TaC), aluminum carbide (AlC),other conductive materials, or any combination thereof.

In one embodiment, portions of the conductive layer and the base layerare removed to even out top portions of the conductive lines 3006 withtop portions of the insulating layer 3004 using a chemical-mechanicalpolishing (“CMP”) technique known to one of ordinary skill in the art ofmicroelectronic device manufacturing.

In one non-limiting example, the thickness of the conductive lines 3006is in an approximate range from about 15 nm to about 1000 nm. In onenon-limiting example, the thickness of the conductive lines 106 is fromabout 20 nm to about 200 nm. In one non-limiting example, the width ofthe conductive lines 3006 is in an approximate range from about 5 nm toabout 500 nm. In one non-limiting example, the spacing (pitch) betweenthe conductive lines 3006 is from about 2 nm to about 500 nm. In morespecific non-limiting example, the spacing (pitch) between theconductive lines 3006 is from about 5 nm to about 50 nm.

In an embodiment, the lower metallization layer Mx is configured toconnect to other metallization layers (not shown). In an embodiment, themetallization layer Mx is configured to provide electrical contact toelectronic devices, e.g., transistor, memories, capacitors, resistors,optoelectronic devices, switches, and any other active and passiveelectronic devices that are separated by an electrically insulatinglayer, for example, an interlayer dielectric, a trench insulation layer,or any other insulating layer known to one of ordinary skill in the artof electronic device manufacturing.

In one or more embodiments, the cap layer 3010 comprises silicon nitride(SiN). The cap layer 3010 protects the insulating layer 3004. In one ormore embodiments, the cap layer 3010 minimizes bowing of the side wallsof the trenches 3008

FIG. 26 is a view 3200 similar to cross-sectional view 3012 of FIG. 25A,after the conductive lines 3006 are recessed according to oneembodiment. The conductive lines 3006 are recessed to a predetermineddepth to form recessed conductive lines 3202. As shown in FIG. 26,trenches 3204 are formed in the insulating layer 3004 and the etch stoplayer 3014. Each trench 3204 has sidewalls 3206 that are portions ofinsulating layer 3004 and a bottom that is a top surface 3208 of therecessed conductive line 3202.

In one embodiment, the depth of the trenches 3204 is from about 10 nm toabout 500 nm. In one embodiment, the depth of the trenches 3204 is fromabout 10% to about 100% of the thickness of the conductive lines. In oneembodiment, the conductive lines 3006 are recessed using one or more ofwet etching, dry etching, or a combination thereof techniques known toone of ordinary skill in the art of electronic device manufacturing.

FIG. 27 is a view 3300 similar to FIG. 6, after a liner 3302 isdeposited on the recessed conductive lines 3202 according to oneembodiment. Liner 3302 is deposited on the bottom and sidewalls of thetrenches 3204, as shown in FIG. 27. In one or more embodiments, liner3302 is deposited on top of cap layer 3010 and into trenches 3204 aroundetch stop layer 3014.

In one embodiment, liner 3302 is deposited to protect the conductivelines 3202 from changing the properties later on in a process (e.g.,during tungsten deposition, or other processes). In one embodiment,liner 3302 is a conductive liner. In another embodiment, liner 3302 is anon-conductive liner. In one embodiment, when liner 3302 is anon-conductive liner, the liner 3302 is removed later on in a process,as described in further detail below. In one embodiment, liner 3302includes titanium nitride (TiN), titanium (Ti), tantalum (Ta), tantalumnitride (TaN), or any combination thereof. In another embodiment, liner3302 is an oxide, e.g., aluminum oxide (Al₂O₃), titanium oxide (TiO₂).In yet another embodiment, liner 3302 is a nitride, e.g., siliconnitride (SiN). In an embodiment, the liner 3302 is deposited to thethickness from about 0.5 nm to about 10 nm.

In an embodiment, the liner 3302 is deposited using an atomic layerdeposition (ALD) technique. In one embodiment, the liner 3302 isdeposited using one of deposition techniques, such as but not limited toa CVD, PVD, MBE, MOCVD, spin-on, or other liner deposition techniquesknow to one of ordinary skill in the art of microelectronic devicemanufacturing.

FIG. 28 is a view 3400 similar to FIG. 27, after a seed gapfill layer3402 is deposited on the liner 3302 according to one embodiment. In oneembodiment, seed gapfill layer 3402 is a self-aligned selective growthseed film. As shown in FIG. 28, seed gapfill layer 3402 is deposited onliner 3302 on the top surface 3208 of the recessed conductive lines3202, the sidewalls 3206 of the trenches 3204 and top portions of theinsulating layer 3004. In one embodiment, seed gapfill layer 3402 is atungsten (W) layer, or other seed gapfill layer to provide selectivegrowth pillars. In some embodiments, seed gapfill layer 3402 is a metalfilm or a metal containing film. Suitable metal films include, but arenot limited to, films including one or more of cobalt (Co), molybdenum(Mo), tungsten (W), tantalum (Ta), titanium (Ti), ruthenium (Ru),rhodium (Rh), copper (Cu), iron (Fe), manganese (Mn), vanadium (V),niobium (Nb), hafnium (Hf), zirconium (Zr), yttrium (Y), aluminum (Al),tin (Sn), chromium (Cr), lanthanum (La), or any combination thereof. Insome embodiments, seed gapfill layer 3402 comprises is a tungsten (W)seed gapfill layer.

In one embodiment, the seed gapfill layer 3402 is deposited using one ofdeposition techniques, such as but not limited to an ALD, a CVD, PVD,MBE, MOCVD, spin-on or other liner deposition techniques known to one ofordinary skill in the art of microelectronic device manufacturing.

FIG. 29 is a view 3500 similar to FIG. 28, after portions of the seedgapfill layer 3402 and the liner 3302 are removed to expose top portionsof the cap layer 3010 according to one embodiment. In one embodiment,the portions of the seed gapfill layer 3402 are removed using one of thechemical-mechanical polishing (CMP) techniques known to one of ordinaryskill in the art of microelectronic device manufacturing.

FIG. 30 is a view 3600 similar to FIG. 29, after self-aligned selectivegrowth pillars 3602 are formed using the seed gapfill layer 3402 on theliner 3302 on the recessed conductive lines 3202 according to oneembodiment. As shown in FIG. 30, an array of the self-aligned selectivegrowth pillars 3602 has the same pattern as the set of the conductivelines 3202. As shown in FIG. 30, the pillars 3602 extend substantiallyorthogonally from the top surfaces of the conductive lines 3202. Asshown in FIG. 30, the pillars 3602 extend along the same direction asthe conductive lines 3202. As shown in FIG. 30, the pillars areseparated by gaps 3606.

In one embodiment, the pillars 3602 are selectively grown from the seedgapfill layer 3402 on portions of the liner 3302 on the conductive lines3202. The pillars 3602 are not grown on portions of the liner 3302 onthe insulating layer 3004, as shown in FIG. 30. In one embodiment,portions of the seed gapfill layer 3402 above the conductive lines 3202are expanded for example, by oxidation, nitridation, or other process togrow pillars 3602. In one embodiment, the seed gapfill layer 3402 isoxidized by exposure to an oxidizing agent or oxidizing conditions totransform the metal or metal containing seed gapfill layer 3402 to metaloxide pillars 3602. In one embodiment, pillars 3602 include an oxide ofone or more metals listed above. In more specific embodiments, pillars3602 include tungsten oxide (e.g., WO, WO₃ and other tungsten oxide).

The oxidizing agent can be any suitable oxidizing agent including, butnot limited to, O₂, O₃, N₂O, H₂O, H₂O₂, CO, CO₂, NH₃, N₂/Ar, N₂/He,N₂/Ar/He, or any combination thereof. In some embodiments, the oxidizingconditions comprise a thermal oxidation, plasma enhanced oxidation,remote plasma oxidation, microwave and radio-frequency oxidation (e.g.,inductively coupled plasma (ICP), capacitively coupled plasma (CCP)).

In one embodiment, the pillars 3602 are formed by oxidation of the seedgapfill layer at any suitable temperature depending on, for example, thecomposition of the seed gapfill layer and the oxidizing agent. In someembodiments, the oxidation occurs at a temperature in an approximaterange of about 25° C. to about 800° C. In some embodiments, theoxidation occurs at a temperature greater than or equal to about 150° C.

In one embodiment, the height 3604 of the pillars 3602 is in anapproximate range from about 5 angstroms (Å) to about 10 microns (μm).

FIG. 31 is a view 3700 similar to FIG. 30, after at least a portion ofthe cap layer 3010 is selectively removed to expose the top surface 3702of the etch stop layer 3014. The cap layer 3010 can be removed byexposing the substrate 3002 to a solution of hot phosphoric acid (i.e.“hot phos”). In one or more embodiments, the entire cap layer 3010 isremoved by exposing the substrate 3002 to a solution of hot phosphoricacid (hot phos). Without intending to be bound by theory, it is thoughtthat the cap layer 3010 serves as a sacrificial layer, introduced at thebeginning of the process flow and removed midway to make the pillarsappear taller.

In one or more embodiments, the solution of hot phosphoric acid (hotphos) has a concentration in the range of 1 wt. % to 99 wt. % in water.In some embodiments, the concentration of phosphoric acid is in a rangeof about 1 wt. % to about 99 wt. %. The substrate 3002 can be treatedwith the solution of hot phosphoric acid (hot phos) for a period in therange of 0.1 minutes to 60 min. In some embodiments, the substrate 3002is treated with the solution of hot phosphoric acid (hot phos) for aperiod in the range of about 2 seconds to about 2 hours, or about 2seconds to about 1 hour. In one or more embodiments, the temperature ofthe hot phosphoric acid solution (hot phos) is in the range of 15° C. to400° C. In some embodiments, the temperature of the hot phosphoric acidsolution (hot phos) is in the range of 25° C. to about 500° C. In someembodiments, the temperature of the hot phosphoric acid solution (hotphos) is greater than 500° C.

In one or more embodiments, the removal of the cap layer 3010 increasesthe aspect ratio. In one or more embodiments, the aspect ratio is in arange of 1:1 to 10:1.

It was unexpectedly and advantageously found by transmission electronmicroscopy (TEM) and electron energy loss spectroscopy (EELS) that thehot phos removal process is selective to the cap layer 3010 and does notaffect the tungsten oxide pillars 3602 or the etch stop layer 3014.

FIG. 32 is a view 3800 similar to FIG. 31, and, after an insulatinglayer 3802 is deposited to overfill the gaps 3606 between the pillars3602 according to one embodiment. As shown in FIG. 32, insulating layer3802 is deposited on the opposing sidewalls 3804 and top portions 3806of the pillars 3602 and through the gaps 3606 on the portions of theinsulating layer 3004 and liner 3302 between the pillars 3602.

In one embodiment, insulating layer 3802 is a low-k gapfill layer. Inone embodiment, insulating layer 3802 is a flowable silicon oxide(FSiOx) layer. In at least some embodiments, insulating layer 3802 is anoxide layer, e.g., silicon dioxide (SiO₂), or any other electricallyinsulating layer determined by an electronic device design. In oneembodiment, insulating layer 3802 is an interlayer dielectric (ILD). Inone embodiment, insulating layer 3802 is a low-k dielectric thatincludes, but is not limited to, materials such as, e.g., silicondioxide, silicon oxide, a carbon based material, e.g., a porous carbonfilm, carbon doped oxide (“CDO”), e.g., carbon doped silicon dioxide,porous silicon dioxide, porous silicon oxide carbide hydride (SiOCH),silicon nitride, or any combination thereof. In one embodiment,insulating layer 3802 is a dielectric material having k-value less than3. In more specific embodiment, insulating layer 3802 is a dielectricmaterial having k-value in an approximate range from about 2.2 to about2.7. In one embodiment, insulating layer 3802 includes a dielectricmaterial having k-value less than 2. In one embodiment, insulating layer3802 represents one of the insulating layers described above withrespect to insulating layer 3004.

In one embodiment, insulating layer 3802 is a low-k interlayerdielectric to isolate one metal line from other metal lines. In oneembodiment, insulating layer 3802 is deposited using one of depositiontechniques, such as but not limited to a CVD, spin-on, an ALD, PVD. MBE,MOCVD, or other low-k insulating layer deposition techniques known toone of ordinary skill in the art of microelectronic devicemanufacturing.

FIG. 33A is a view 3900 similar to FIG. 32, after a portion of theinsulating layer 3802 is removed to expose the top portions 3806 of thepillars 3602 according to one embodiment. In one embodiment, the portionof the insulating layer 3802 is removed using a CMP technique known toone of ordinary skill in the art of microelectronic devicemanufacturing. In one embodiment, the portion of the insulating layer3802 is etched back to expose the top portions 3806 of the pillars 3602using one or more of the dry and wet etching techniques known to one ofordinary skill in the art of microelectronic device manufacturing.

FIG. 33B is a view 3910 similar to FIG. 30, after an insulating layer3802 is deposited to underfill (partially fill) the gaps 3606 betweenthe pillars 3602 according to another embodiment. As shown in FIG. 33B,insulating layer 3802 is deposited through gaps 3606 on lower portionsof opposing sidewalls 3804 of the pillars 3602 and the portions of theinsulating layer 3004 and liner 3302 between pillars 3602. In oneembodiment, insulating layer 3802 is deposited to a predeterminedthickness to expose the top portions 3806 and upper portions of theopposing sidewalls 3804 of the pillars 3602.

In one embodiment, insulating layer 3802 is deposited using one ofdeposition techniques, such as but not limited to a CVD, spin-on, anALD, PVD, MBE, MOCVD, or other low-k insulating layer depositiontechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing. In another embodiment, insulating layer 3802 isdeposited to overfill the gaps 3606 between the pillars 3602, asdescribed with respect to FIG. 32, and then a portion of the insulatinglayer 3802 is etched back to expose upper portions 3808 of the sidewalls3804 and top portions 3806 of the pillars 3602 using one or more of thedry and wet etching techniques known to one of ordinary skill in the artof microelectronic device manufacturing.

FIG. 34 is a view 4000 similar to FIG. 32 after the self-alignedselectively grown pillars 3602 are selectively removed to form trenches4002 according to one embodiment. As shown in FIG. 34, the pillars 3602are removed selectively to the insulating layer 3802 and liner 3302. Inanother embodiment, when liner 3302 is a non-conductive liner, liner3302 is removed. In one embodiment, the pillars 3602 and liner 3302 areremoved selectively to the insulating layers 3802 and 3004 andconductive lines 3202 and etch stop layer 3014. As shown in FIG. 34,trenches 4002 are formed in the insulating layers 3802 and 3004.Trenches 4002 extend along the recessed conductive lines 3202. As shownin FIG. 34, each trench 4002 has a bottom that is a bottom portion 4004of liner 3302 and opposing sidewalls that include a sidewall portion4006 of liner 3302 and a portion of insulating layer 3802. In anotherembodiment, when liner 3302 is removed, each trench 4002 has a bottomthat is recessed conductive line 3202 and opposing sidewalls thatinclude portions of insulating layers 3802 and 3004. Generally, theaspect ratio of the trench refers to the ratio of the depth of thetrench to the width of the trench. In one embodiment, the aspect ratioof each trench 4002 is in an approximate range from about 1:1 to about200:1.

In one embodiment, the pillars 3602 are selectively removed using one ormore of the dry and wet etching techniques known to one of ordinaryskill in the art of electronic device manufacturing. In one embodiment,the pillars 3602 are selectively wet etched by e.g., 5 wt. % of ammoniumhydroxide (NH₄OH) aqueous solution at the temperature of about 80degrees C. In one embodiment, hydrogen peroxide (H₂O₂) is added to the 5wt. % NH₄OH aqueous solution to increase the etching rate of the pillars3602. In one embodiment, the pillars 3602 are selectively wet etchedusing hydrofluoric acid (HF) and nitric acid (HNO₃) in a ratio of 1:1.In one embodiment, the pillars 3602 are selectively wet etched using HFand HNO₃ in a ratio of 3:7 respectively. In one embodiment, the pillars3602 are selectively wet etched using HF and HNO₃ in a ratio of 4:1,respectively. In one embodiment, the pillars 3602 are selectively wetetched using HF and HNO₃ in a ratio of 30%:70%, respectively. In oneembodiment, the pillars 3602 including tungsten (W), titanium (Ti), orboth titanium and tungsten are selectively wet etched using NH₄OH andH₂O₂ in a ratio of 1:2, respectively. In one embodiment, the pillars3602 are selectively wet etched using 305 grams of potassiumferricyanide (K₃Fe(CN)₆), 44.5 grams of sodium hydroxide (NaOH) and 1000ml of water (H₂O). In one embodiment, the pillars 3602 are selectivelywet etched using diluted or concentrated one or more of the chemistriesincluding hydrochloric acid (HCl), HNO₃, sulfuric acid (H₂SO₄), HF, andH₂O₂. In one embodiment, the pillars 3602 are selectively wet etchedusing HF, HNO₃ and acetic acid (CH₃COOH) in a ratio of 4:4:3,respectively. In one embodiment, the pillars 3602 are selectively dryetched using a bromotrifluoromethane (CBrF3) reactive ion etching (RIE)technique. In one embodiment, the pillars 602 are selectively dry etchedusing a chlorine, fluorine, bromine or any combination thereof basedchemistries. In one embodiment, the pillars 3602 are selectively wetetched using hot or warm Aqua Regia mixture including HCl and HNO₃ in aratio of 3:1, respectively. In one embodiment, the pillars 3602 areselectively etched using alkali with oxidizers (potassium nitrate (KNO₃)and lead dioxide (PbO₂)). In one embodiment, the liner 3302 isselectively removed using one or more of the dry and wet etchingtechniques known to one of ordinary skill in the art of electronicdevice manufacturing.

FIG. 35 is a view 4100 and that is similar to FIG. 34 after aninsulating layer 4102 is deposited into trenches 4002 according to oneembodiment. As shown in FIG. 35, insulating layer 4102 overfills thetrenches 4002 so that portions of the insulating layer 4102 aredeposited on the top portions of the insulating layer 3802. In oneembodiment, the thickness of the insulating layer 4102 is greater orsimilar to the thickness of the insulating layer 3802. In oneembodiment, the thickness 4104 is at least two or three times greaterthan the thickness of the insulating layer 3802. In another embodiment,portions of the insulating layer 4102 are removed using one or more ofCMP or a back etch technique to even out with the top portions of theinsulating layer 3802, and then another insulating layer (not shown) isdeposited onto the top portions of the insulating layer 3802 andinsulating layer 4102. As shown in FIG. 35, insulating layer 4102 isdeposited on the sidewalls and bottom of the trenches 4004. As shown inFIG. 35, the insulating layer 4102 is deposited on the liner 3302 andportions of the insulating layer 3802. In another embodiment, when theliner 3302 is removed, the insulating layer 4102 is directly depositedon the recessed conductive lines 3202 and portions of the insulatinglayer 3004 and insulating layer 3802. In one embodiment, the insulatinglayer 4102 is etch selective to the insulating layer 3802. Generally,etch selectivity between two materials is defined as the ratio betweentheir etching rates at similar etching conditions. In one embodiment,the ratio of the etching rate of the insulating layer 4102 to that ofthe insulating layer 3802 is at least 5:1. In one embodiment, the ratioof the etching rates of the insulating layer 4102 to that of theinsulating layer 3802 is in an approximate range from about 2:1 to about20:1.

In one embodiment, insulating layer 4102 is a low-k gapfill layer. Inone embodiment, insulating layer 4102 is a flowable silicon oxidecarbide (FSiOC) layer. In some other embodiments, insulating layer 4102is an oxide layer, e.g., silicon dioxide, or any other electricallyinsulating layer determined by an electronic device design. In oneembodiment, insulating layer 4102 is an interlayer dielectric (ILD). Inone embodiment, insulating layer 4102 is a low-k dielectric thatincludes, but is not limited to, materials such as, e.g., silicondioxide, silicon oxide, a carbon based material, e.g., a porous carbonfilm carbon doped oxide (“CDO”), e.g., carbon doped silicon dioxide,porous silicon dioxide, porous silicon oxide carbide hydride (SiOCH),silicon nitride, or any combination thereof. In one embodiment,insulating layer 4102 is a dielectric material having k-value less than3. In more specific embodiment, insulating layer 4102 is a dielectricmaterial having k-value in an approximate range from about 2.2 to about2.7. In one embodiment, insulating layer 4102 includes a dielectricmaterial having k-value less than 2. In one embodiment, insulating layer4102 represents one of the insulating layers described above withrespect to insulating layer 3004 and insulating layer 3802.

In one embodiment, insulating layer 4102 is a low-k interlayerdielectric to isolate one metal line from other metal lines. In oneembodiment, insulating layer 4102 is deposited using one of depositiontechniques, such as but not limited to a CVD, spin-on, an ALD, PVD, MBE,MOCVD, or other low-k insulating layer deposition techniques known toone of ordinary skill in the art of microelectronic devicemanufacturing.

FIG. 36 is a view 4200 after a hard mask layer 4202 is deposited oninsulating layer 4204 according to one embodiment. FIG. 36 is differentfrom FIG. 35 in that the liner 3302 is removed, so that insulating layer4204 is directly deposited on the recessed conductive lines 3202 andportions of the insulating layer 3004 and insulating layer 3802, asdescribed above. In one embodiment, hard mask layer 1202 is ametallization layer hard mask. As shown in FIG. 35, the hard mask layer4202 is patterned to define a plurality of trenches 4206. As shown inFIG. 35, the trenches 4206 extend along an Y-axis (direction) 124 thatcrosses an X-axis (direction) 122 at an angle. In one embodiment,direction 124 is substantially perpendicular to direction 124. In oneembodiment, patterned hard mask layer 4202 is a carbon hard mask layer,a metal oxide hard mask layer, a metal nitride hard mask layer, asilicon nitride hard mask layer, a silicon oxide hard mask layer, acarbide hard mask layer, or other hard mask layer known to one ofordinary skill in the art of microelectronic device manufacturing. Inone embodiment, the patterned hard mask layer 4202 is formed using oneor more hard mask patterning techniques known to one of ordinary skillin the art of microelectronic device manufacturing. In one embodiment,the insulating layer 4102 is etched through a patterned hard mask layerto form trenches 4206 using one or more of etching techniques known toone of ordinary skill in the art of microelectronic devicemanufacturing. In one embodiment, the size of trenches in the insulatinglayer 4102 is determined by the size of conductive lines formed later onin a process.

FIG. 37A is a view 4300 similar to FIG. 36, after a mask layer 4302 isdeposited on an insulating layer 4304 on a patterned hard mask layer4202 according to one embodiment. FIG. 37B is a cross-sectional view4400 of FIG. 37A along an axis F-F′.

As shown in FIGS. 37A and 37B, an opening 4306 is formed in mask layer4202. Opening 4306 is formed above one of the conductive lines 3202, asshown in FIGS. 37A and 37B. In one embodiment, the opening 4306 definesa trench portion of the fully self-aligned via formed later on in aprocess.

In one embodiment, mask layer 4302 includes a photoresist layer. In oneembodiment, mask layer 4302 includes one or more hard mask layers. Inone embodiment, the insulating layer 4304 is a hard mask layer. In oneembodiment, insulating layer 4304 includes a bottom anti-reflectivecoating (BARC) layer. In one embodiment, insulating layer 1304 includesa titanium nitride (TiN) layer, a tungsten carbide (WC) layer, atungsten bromide carbide (WBC) layer, a carbon hard mask layer, a metaloxide hard mask layer, a metal nitride hard mask layer, a siliconnitride hard mask layer, a silicon oxide hard mask layer, a carbide hardmask layer, other hard mask layer, or any combination thereof. In oneembodiment, insulating layer 4304 represents one of the insulatinglayers described above. In one embodiment, mask layer 4302 is depositedusing one or more mask layer deposition techniques known to one ofordinary skill in the art of microelectronic device manufacturing. Inone embodiment, insulating layer 4304 is deposited using one ofdeposition techniques, such as but not limited to a CVD, PVD, MBE,NOCVD, spin-on, or other insulating layer deposition techniques known toone of ordinary skill in the art of microelectronic devicemanufacturing. In one embodiment, the opening 4306 is formed using oneor more of the patterning and etching techniques known to one ofordinary skill in the art of microelectronic device manufacturing.

FIG. 38A is a view 4500 similar to FIG. 37B after the insulating layer4304 and patterned hard mask layer 4202 are selectively etched throughopening 4306 to form an opening 4402 according to one embodiment. FIG.38B is a view 4600 similar to FIG. 37A after the insulating layer 4304and insulating layer 4102 are selectively etched through opening 4306 toform opening 4402 according to one embodiment.

FIG. 38B is different from FIG. 38A in that FIG. 38B shows a cut throughopening 4402 along X-axis 122 and Y-axis 124. As shown in FIGS. 38A and38B, opening 4402 includes a via portion 4404 and a trench portion 4406.As shown in FIGS. 38A and 38B, via portion 4404 of the opening 4402 islimited along Y-axis 124 by insulating layer 3802. Via portion 4404 ofthe opening 4402 is self-aligned along Y-axis 124 to one of theconductive lines 3202. As shown in FIGS. 38A and 38B, trench portion4406 is limited along X-axis 122 by the features of the hard mask layer4202 that extend along Y-axis 124. In one embodiment, insulating layer4102 is selectively etched relative to the insulating layer 3802 to formopening 4402.

In one embodiment, patterned hard mask layer 4202 is selectively etchedrelative to the insulating layer 3802 to form opening 4402. As shown inFIGS. 38A and 38B, mask layer 4302 and insulating layer 4304 areremoved. In one embodiment, mask layer 4302 is removed using one or moreof the mask layer removal techniques known to one of ordinary skill inthe art of microelectronic device manufacturing. In one embodiment,insulating layer 4304 is removed using one or more of the etchingtechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing.

FIG. 39A is a view 4700 similar to FIG. 35, after a mask layer 4502 isdeposited on the exposed insulating layer 3802 and insulating layer 4102according to one embodiment. FIG. 39B is a top view 4710 of theelectronic device structure depicted in FIG. 39A. As shown in FIG. 39A,a portion of the insulating layer 4102 is removed to even out topportions of the insulating layer 3802 with top portions of theinsulating layer 4102. As shown in FIGS. 39A and 39B, mask layer 4502has an opening 4506 to expose hard mask layer 4502.

In one embodiment, the portion of the insulating layer 4102 is removedusing a CMP technique known to one of ordinary skill in the art ofmicroelectronic device manufacturing. In one embodiment, a portion ofthe insulating layer 4102 is etched back to expose the top portion ofthe insulating layer 3802. In another embodiment, a portion of theinsulating layer 3802 is etched back to a predetermined depth to exposeupper portions of the sidewalls and top portions of the insulating layer4102 in the trenches 4002. In one embodiment, the portion of theinsulating layer 3802 is etched back using one or more of the dry andwet etching techniques known to one of ordinary skill in the art ofmicroelectronic device manufacturing.

In one embodiment, mask layer 4502 includes a photoresist layer. In oneembodiment, mask layer 4502 includes one or more hard mask layers. Inone embodiment, mask layer 4502 is a tri-layer mask stack, e.g., a 193nm immersion (193 i) or EUV resist mask on a middle layer (ML) (e.g., asilicon containing organic layer or a metal containing dielectric layer)on a bottom anti-reflective coating (BARC) layer on a silicon oxide hardmask. In one embodiment, the hard mask layer 4504 is a metallizationlayer hard mask to pattern the conductive lines of the nextmetallization layer. In one embodiment, hard mask layer 4504 includes atitanium nitride (TiN) layer, a tungsten carbide (WC) layer, a tungstenbromide carbide (WBC) layer, a carbon hard mask layer, a metal oxidehard mask layer, a metal nitride hard mask layer, a silicon nitride hardmask layer, a silicon oxide hard mask layer, a carbide hard mask layer,other hard mask layer or any combination thereof. In one embodiment,hard mask layer 1504 represents one of the hard mask layers describedabove.

In one embodiment, the insulating layer 3802 and the insulating layer4102 are patterned and etched using hard mask 4504 to form trenchesusing one or more patterning and etching techniques known to one orordinary skill in the art of microelectronic device manufacturing. Inone embodiment, the size of trenches in the insulating layer 3802 andinsulating layer 4102 is determined by the size of conductive linesformed later on in a process.

In one embodiment, the mask layer 4502 is deposited using one or more ofthe mask deposition techniques known to one of ordinary skill in the artof microelectronic device manufacturing. In one embodiment, hard masklayer 4504 is deposited using one or more hard mask layer depositiontechniques, such as but not limited to a CVD, PVD, MBE, MOCVD, spin-on,or other hard mask deposition known to one of ordinary skill in the artof microelectronic device manufacturing. In one embodiment, the opening4506 is formed using one or more of the patterning and etchingtechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing.

FIG. 40A is a view 4800 similar to FIG. 39A, after portions of the hardmask layer 4504, insulating layer 3802 and insulating layer 4102 areremoved through opening 4506 to form an opening 4602 in insulating layer3802 according to one embodiment. FIG. 40B is a top view 4820 of theelectronic device structure depicted in FIG. 40A. In one embodiment,opening 4602 is a trench opening for a via. As shown in FIGS. 40A and40B, opening 4602 includes a bottom 4612 that includes a portion 4604 ofthe insulating layer 4102 between portions 4606 and 4608 of theinsulating layer 3802. As shown in FIGS. 40A and 40B, opening 4602includes opposing sidewalls 4610 that include portions of the insulatinglayer 3802. In one embodiment, each sidewall 4610 is substantiallyorthogonal to bottom 4612. In another embodiment, each sidewall 4610 isslanted relative to bottom 4612 at an angle other than 90 degrees, sothat an upper portion of the opening 4602 is greater than a lowerportion of the opening 4602.

In one embodiment, opening 4602 having slanted sidewalls is formed usingan angled non-selective etch. In one embodiment, hard mask layer 4504 isremoved using one or more of wet etching, dry etching, or a combinationthereof techniques known to one of ordinary skill in the art ofmicroelectronic device manufacturing. In one embodiment, insulatinglayer 3802 and insulating layer 4102 are removed using a non-selectiveetch in a trench first dual damascene process. In one embodiment,insulating layer 3802 and insulating layer 4102 are etched down to thedepth that is determined by time. In another embodiment, insulatinglayer 3802 and insulating layer 4102 are etched non-selectively down toetch stop layer 3014. In one embodiment, insulating layer 3802 andinsulating layer 4102 are non-selectively etched using one or more ofwet etching, dry etching, or a combination thereof techniques known toone of ordinary skill in the art of electronic device manufacturing.

FIG. 41A is a view 4900 similar to FIG. 40A, after a fully self-alignedopening 4702 is formed in insulating layer 3802 according to oneembodiment. FIG. 41B is a top view 4720 of the electronic devicestructure depicted in FIG. 41A. As shown in FIGS. 41A and 41B, masklayer 4502 is removed. Mask layer 4502 can be removed using one of themask layer removal techniques known to one of ordinary skill in the artof microelectronic device manufacturing. A patterned mask layer 4714 isformed on hard mask layer 4504. As shown in FIG. 41B, patterned masklayer 4714 is deposited on the hard mask layer 4504 and into opening4602. Patterned mask layer 4714 has an opening 4708. Patterned masklayer 4714 can be formed using one or more of the mask layer depositing,patterning and etching techniques known to one of ordinary skill in theart of microelectronic device manufacturing.

Fully self-aligned opening 4702 is formed through mask opening 4708.Fully self-aligned opening 4702 includes a trench opening 4706 and a viaopening 4704, as shown in FIGS. 41A and 41B. Via opening 4704 isunderneath trench opening 4706. In one embodiment, trench opening 4706is the part of the that is exposed through opening 4708.

In one embodiment, via opening 4704 is formed by selectively etchinginsulating layer 4102 relative to the insulating layer 3802 through maskopening 4708 and trench opening 4706. In one embodiment, trench opening4706 extends along Y-axis 124. As shown in FIG. 41B, trench opening 4706is greater along Y-axis 124 than along X-axis 122.

In one embodiment, trench opening 4706 of the opening 4702 isself-aligned along X-axis 122 between the features of the hard masklayer 4504 that are used to pattern the upper metallization layerconductive lines that extend along Y-axis 124 (not shown). The viaopening 4704 of the opening 4702 is self-aligned along Y-axis 124 by theinsulating layer 3802 that is left intact by selectively etching theportion 4604 of the insulating layer 4102 relative to the insulatinglayer 3802. This provides an advantage as the size of the trench opening4706 does not need to be limited to the size of the cross-sectionbetween the conductive line 4716 and one of the conductive lines of theupper metallization layer that provides more flexibility for thelithography equipment. As the portion 4604 is selectively removedrelative to the insulating layer 3802, the size of the trench openingincreases.

As shown in FIGS. 40A and 40B, the portion 4604 is self-aligned with aconductive line 4716 that is one of the lower metallization layerconductive lines 3202. That is, the opening 4702 is self-aligned alongboth X and Y axes.

FIG. 41A is different from FIG. 40A in that FIG. 41A illustrates trenchopening 4706 having slanted sidewalls 4710. Each sidewall 4710 is at anangle other than 90 degrees to the top surface of the substrate 3002, sothat an upper portion of the trench opening 4706 is greater than a lowerportion of the trench opening 4706. In another embodiment, the sidewalls4710 are substantially orthogonal to the top surface of the substrate3002.

In one embodiment, mask layer 4714 includes a photoresist layer. In oneembodiment, mask layer 4714 includes one or more hard mask layers. Inone embodiment, mask layer 4714 is tri-layer mask stack, e.g., a 193 ior EUV resist mask on a ML (e.g., a silicon containing organic layer ora metal containing dielectric layer) on a BARC layer on a silicon oxidehard mask. As shown in FIGS. 41A and 41B, via opening 4704 exposes aportion 4712 of the liner 3302 on conductive line 4716. In anotherembodiment, when the liner 3302 is removed, the via opening 4704 exposesconductive line 4716.

FIG. 42A is a view 4930 similar to FIG. 41A, after an uppermetallization layer My comprising conductive lines extending alongY-axis 124 is formed according to one embodiment. FIG. 42B is a top view4950 of the electronic device structure depicted in FIG. 42A. FIG. 42Ais a cross-sectional view of FIG. 42B along an axis G-G′. As shown inFIG. 42A, mask layer 4502 and hard mask layer 4504 are removed. In oneembodiment, each of the mask layer 4502 and hard mask layer 4504 isremoved using one or more of the hard mask layer removal techniques knowin one of ordinary skill in the art of microelectronic devicemanufacturing.

An upper metallization layer My includes a set of conductive lines 4802that extend on portions of insulating layer 4102 and portions insulatinglayer 3802. As shown in FIG. 42B, the portions of the insulating layer4102 are between the portions of the insulating layer 3802. Conductivelines 4802 extend along Y-axis 124. A fully self-aligned via 4824includes a trench portion 4804 and a via portion 4806. Via portion 4806is underneath trench portion 4804. The fully self-aligned via 4824 isbetween the lower metallization layer comprising conductive lines 4802that extend along X-axis 122 and the upper metallization layercomprising conductive lines 4802. As shown in FIGS. 42A and 42B, the viaportion 4806 is on liner 3302 on conductive line 4716. As shown in FIGS.42A and 42B, the via portion 4806 of the via 4824 is self-aligned alongthe Y-axis 124 to conductive line 4716 that is one of the conductivelines 3202. The via portion 4806 of the via 4824 is self-aligned alongthe X-axis (direction) 122 to a conductive line 4822 that is one of theconductive lines 4802. In one embodiment, when liner 3302 is removed,the via portion 4806 is directly on conductive line 4716. As shown inFIGS. 42A and 42B, the via portion 4806 is a part of the conductive line4822. As shown in FIGS. 42A and 42B, the size of the via portion 4806 isdetermined by the size of the cross-section between the conductive line4716 and conductive line 4822.

In one embodiment, forming the conductive lines 4802 and via 4824involves filling the trenches in the insulating layer and the opening4702 with a layer of conductive material. In one embodiment, a baselayer (not shown) is first deposited on the internal sidewalls andbottom of the trenches and the opening 4702, and then the conductivelayer is deposited on the base layer. In one embodiment, the base layerincludes a conductive seed layer (not shown) deposited on a conductivebarrier layer (not shown). The seed layer can include copper, and theconductive barrier layer can include aluminum, titanium, tantalum,tantalum nitride, and the like metals. The conductive barrier layer canbe used to prevent diffusion of the conductive material from the seedlayer, e.g., copper, into the insulating layer. Additionally, theconductive barrier layer can be used to provide adhesion for the seedlayer (e.g., copper).

In one embodiment, to form the base layer, the conductive barrier layeris deposited onto the sidewalls and bottom of the trenches, and then theseed layer is deposited on the conductive barrier layer. In anotherembodiment, the conductive base layer includes the seed layer that isdirectly deposited onto the sidewalls and bottom of the trenches. Eachof the conductive barrier layer and seed layer may be deposited usingany thin film deposition technique known to one of ordinary skill in theart of semiconductor manufacturing, e.g., sputtering, blanketdeposition, and the like. In one embodiment, each of the conductivebarrier layer and the seed layer has the thickness in an approximaterange from about 1 nm to about 100 nm. In one embodiment, the barrierlayer may be a thin dielectric that has been etched to establishconductivity to the metal layer below. In one embodiment, the barrierlayer may be omitted altogether and appropriate doping of the copperline may be used to make a “self-forming barrier”.

In one embodiment, the conductive layer e.g., copper or cobalt, isdeposited onto the seed layer of base later of copper, by anelectroplating process. In one embodiment, the conductive layer isdeposited into the trenches using a damascene process known to one ofordinary skill in the art of microelectronic device manufacturing. Inone embodiment, the conductive layer is deposited onto the seed layer inthe trenches and in the opening 4702 using a selective depositiontechnique, such as but not limited to electroplating, electrolysis, aCVD, PVD, MBE, MOCVD, ALD, spin-on, or other deposition techniques knownto one of ordinary skill in the art of microelectronic devicemanufacturing.

In one embodiment, the choice of a material for conductive layer for theconductive lines 4802 and via 4824 determines the choice of a materialfor the seed layer. For example, if the material for the conductivelines 4802 and via 4824 includes copper, the material for the seed layeralso includes copper. In one embodiment, the conductive lines 4802 andvia 4824 include a metal, for example, copper (Cu), ruthenium (Ru),nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn),titanium (Ti), aluminum (Al), hafnium (Hf), tantalum (Ta), tungsten (W),vanadium (V), molybdenum (Mo), palladium (Pd), gold (Au), silver (Ag),platinum (Pt), indium (In), tin (Sn), lead (Pb), antimony (Sb), bismuth(Bi), zinc (Zn), cadmium (Cd), or any combination thereof.

In alternative embodiments, examples of the conductive materials thatmay be used for the conductive lines 4802 and via 4824 include metals,e.g., copper, tantalum, tungsten, ruthenium, titanium, hafnium,zirconium, aluminum, silver, tin, lead, metal alloys, metal carbides,e.g., hafnium carbide, zirconium carbide, titanium carbide, tantalumcarbide, aluminum carbide, other conductive materials, or anycombination thereof.

In one embodiment, portions of the conductive layer and the base layerare removed to even out top portions of the conductive lines 4802 withtop portions of the insulating layer 3802 and insulating layer 4102using a chemical-mechanical polishing (“CMP”) technique known to one ofordinary skill in the art of microelectronic device manufacturing.

In one non-limiting example, the thickness of the conductive lines 4802is in an approximate range from about 15 nm to about 1000 nm. In onenon-limiting example, the thickness of the conductive lines 4802 is fromabout 20 nm to about 200 nm. In one non-limiting example, the width ofthe conductive lines 4802 is in an approximate range from about 5 nm toabout 500 nm. In one non-limiting example, the spacing (pitch) betweenthe conductive lines 4802 is from about 2 nm to about 500 nm. In morespecific non-limiting example, the spacing (pitch) between theconductive lines 1802 is from about 5 nm to about 50 nm.

FIGS. 43 through 47 (including both A and B designations) illustrateanother embodiment of the disclosure. FIG. 43A is a view 4960 similar toFIG. 34, after a mask layer 4904 is deposited on a hard mask layer 4902on the insulating layer 4102 according to one embodiment. FIG. 43B is atop view 4970 of the electronic device structure depicted in FIG. 43A.As shown in FIGS. 43A and 43B, mask layer 4904 has an opening 4906 toexpose hard mask layer 4902.

In one embodiment, mask layer 4904 includes a photoresist layer. In oneembodiment, mask layer 4904 includes one or more hard mask layers. Inone embodiment, mask layer 4904 is a tri-layer mask stack, e.g., a 193nm immersion (193 i) or EUV resist mask on a middle layer (ML) (e.g., asilicon containing organic layer or a metal containing dielectric layer)on a bottom anti-reflective coating (BARC) layer on a silicon oxide hardmask. In one embodiment, the hard mask layer 4902 is a metallizationlayer hard mask to pattern the conductive lines of the nextmetallization layer. In one embodiment, hard mask layer 4902 includes atitanium nitride (TiN) layer, a tungsten carbide (WC) layer, a tungstenbromide carbide (WBC) layer, a carbon hard mask layer, a metal oxidehard mask layer, a metal nitride hard mask layer, a silicon nitride hardmask layer, a silicon oxide hard mask layer, a carbide hard mask layer,other hard mask layer or any combination thereof. In one embodiment,hard mask layer 4902 represents one of the hard mask layers describedabove.

In one embodiment, the mask layer 4904 is deposited using one or more ofthe mask deposition techniques known to one of ordinary skill in the artof microelectronic device manufacturing. In one embodiment, hard masklayer 4902 is deposited using one or more hard mask layer depositiontechniques, such as but not limited to a CVD, PVD, MBE, MOCVD, spin-on,or other hard mask deposition known to one of ordinary skill in the artof microelectronic device manufacturing. In one embodiment, the opening4906 is formed using one or more of the patterning and etchingtechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing.

FIG. 44A is a view 5000 similar to FIG. 43A, after portions of the hardmask layer 4902 and insulating layer 4102 are removed through opening4906 to form an opening 5002 in insulating layer 4102 according to oneembodiment. FIG. 44B is a top view 5050 of the electronic devicestructure depicted in FIG. 44A. In one embodiment, opening 5002 is atrench opening for a via. As shown in FIGS. 44A and 44B, opening 5002includes a bottom 5010 that includes a portion 5004 of the insulatinglayer 4102 between portions 5006 and 5008 of the insulating layer 3802.As shown in FIGS. 44A and 44B, opening 5002 includes opposing sidewalls5012 that include portions of the insulating layer 4102. In oneembodiment, each sidewall 5012 is substantially orthogonal to bottom5010. In another embodiment, each sidewall 5012 is slanted relative tobottom 5010 at an angle other than 90 degrees, so that an upper portionof the opening 5002 is greater than a lower portion of the opening 5002.

In one embodiment, opening 5002 having slanted sidewalls is formed usingan angled non-selective etch. In one embodiment, hard mask layer 4902 isremoved using one or more of wet etching, dry etching, or a combinationthereof techniques known to one of ordinary skill in the art ofmicroelectronic device manufacturing. In one embodiment, insulatinglayer 4102 is removed using a non-selective etch in a trench first dualdamascene process. In one embodiment, insulating layer 4102 is etcheddown to the depth that is determined by time. In another embodiment,insulating layer 4102 is etched non-selectively down to etch stop layer3014. In one embodiment, insulating layer 4102 is non-selectively etchedusing one or more of wet etching, dry etching, or a combination thereoftechniques known to one of ordinary skill in the art of electronicdevice manufacturing.

FIG. 45A is a view 5100 similar to FIG. 44A, after mask layer 4904 isremoved, planarization filling layer 5102 is formed and mask layer 5104with a fully opening 5106 is formed according to one embodiment. FIG.45B is a top view 5110 of the electronic device structure depicted inFIG. 45A. As shown in FIGS. 45A and 45B, mask layer 4904 is removed.Mask layer 4904 can be removed using one of the mask layer removaltechniques known to one of ordinary skill in the art of microelectronicdevice manufacturing. A planarization filling layer 5102 is formed inopening 5002 onto the tops of exposed insulating layer 3802 andinsulating layer 4102. The planarization filling layer 5102 illustratedis formed so that an overburden 5108 is formed on hard mask layer 4902.In some embodiments, the planarization filling layer 5102 is formed tobe substantially coplanar with the hard mask layer 4902. In someembodiments, the planarization filling layer 5102 is planarized, forexample, by a CMP process. The planarization filling layer 5102 can beany suitable material including, but not limited to, BARC (BottomAnti-Reflective Coating) layer (e.g., spin-on polymers containing C andH, or Si), DARC (Dielectric Anti-Reflective Coating) layer or an OPL(Organic Planarization Layer). The planarization filling layer 5102 ofsome embodiments is deposited by CVD or ALD. In some embodiments, theplanarization filling layer 5102 comprises one or more atoms of Si, O,N, C or H.

A patterned mask layer 5104 is formed on hard mask layer 4902. As shownin FIG. 45B, patterned mask layer 5104 is deposited on the planarizationfilling layer 5102. Patterned mask layer 5104 has an opening 5106.Patterned mask layer 5104 can be formed using one or more of the masklayer depositing, patterning and etching techniques known to one ofordinary skill in the art of microelectronic device manufacturing.

In one embodiment, mask layer 5104 includes a photoresist layer. In oneembodiment, mask layer 5104 includes one or more hard mask layers. Inone embodiment, mask layer 5104 is tri-layer mask stack, e.g., a 193 ior EUV resist mask on a ML (e.g., a silicon containing organic layer ora metal containing dielectric layer) on a BARC layer on a silicon oxidehard mask.

FIG. 46A is a view 2200 similar to FIG. 45A, after removing theplanarization filling layer 5102 and insulating layer 4102 throughopening 5106. The embodiment illustrated has the patterned mask layer5104 and planarization filling layer 5102 removed from hard mask layer4902. A fully self-aligned opening 5202 is formed through opening 5106.Fully self-aligned opening 5202 includes a trench opening 5206 and a viaopening 5204, as shown in FIGS. 46A and 46B. Via opening 5204 isunderneath trench opening 5206.

In one or more embodiments, via opening 5204 is formed by selectivelyetching insulating layer 4102 relative to the insulating layer 3802through opening 5106 and trench opening 5206. In one embodiment, trenchopening 2206 extends along Y-axis 124. As shown in FIG. 46B, trenchopening 5206 is greater along Y-axis 124 than along X-axis 122.

In one embodiment, trench opening 5206 of the opening 5202 isself-aligned along X-axis between the features of the hard mask layer4902 that are used to pattern the upper metallization layer conductivelines that extend along Y-axis 124 (not shown). The via opening 5204 ofthe opening 5202 is self-aligned along Y-axis 124 by the insulatinglayer 3802 that is left intact by selectively etching the portion 5004of the insulating layer 4102 relative to the insulating layer 3802. Thisprovides an advantage as the size of the trench opening 5206 does notneed to be limited to the size of the cross-section between theconductive line 5216 and one of the conductive lines of the uppermetallization layer that provides more flexibility for the lithographyequipment. As the portion 2004 is selectively removed relative to theinsulating layer 3802, the size of the trench opening increases.

As shown in FIGS. 44A and 44B, the portion 5004 is self-aligned with aconductive line 5216 that is one of the lower metallization layerconductive lines 3202. That is, the opening 5202 is self-aligned alongboth X and Y axes.

FIG. 46A illustrates trench opening 5206 having sidewalls 5210 that aresubstantially orthogonal to the top surface of the substrate 3002. Insome embodiments, each sidewall 5210 is at an angle other than 90degrees to the top surface of the substrate 3002, so that an upperportion of the trench opening 5206 is greater than a lower portion ofthe trench opening 5206.

As shown in FIGS. 46A and 46B, via opening 5204 exposes a portion 5212of the liner 3302 on conductive line 5216. In another embodiment, whenthe liner 302 is removed, the via opening 5204 exposes conductive line5216.

FIG. 47A is a view 5300 similar to FIG. 46A, after an uppermetallization layer My comprising conductive lines extending alongY-axis 124 is formed according to one embodiment. FIG. 47B is a top view5330 of the electronic device structure depicted in FIG. 47A. FIG. 47Ais a cross-sectional view of FIG. 47B taken along an axis H-H′. As shownin FIG. 47A, hard mask layer 4902 is removed. In one embodiment, hardmask layer 4902 is removed using one or more of the hard mask layerremoval techniques know in one of ordinary skill in the art ofmicroelectronic device manufacturing.

An upper metallization layer My includes a set of conductive lines 5302that extend on portions of insulating layer 3802. In the embodimentillustrated in FIG. 47A, the conductive lines 5302 are filled to beco-planar with the top of insulating layer 4102. In some embodiments,the conductive lines 5302 extend above the top surface of insulatinglayer 4102, similar to that shown in FIG. 42A.

As shown in FIG. 47B, the portions of the insulating layer 4102 arebetween the portions of the insulating layer 3802. Conductive lines 5302extend along Y-axis 124. A fully self-aligned via 5324 includes a trenchportion 5304 and a via portion 5306. Via portion 5306 is underneathtrench portion 5304. The fully self-aligned via 5324 is between thelower metallization layer comprising conductive lines 3202 that extendalong X-axis 122 and the upper metallization layer comprising conductivelines 5302. As shown in FIGS. 47A and 47B, the via portion 5306 is onliner 3302 on conductive line 5216. As shown in FIGS. 47A and 47B, thevia portion 5306 of the via 5324 is self-aligned along the Y-axis 124 toconductive line 5216 that is one of the conductive lines 3202. Thetrench portion 5306 of the via 5324 is self-aligned along the X-axis122. In one embodiment, when liner 3302 is removed, the via portion 5306is directly on conductive line 5216.

In one embodiment, forming the conductive lines 5302 and via 5324involves filling the trenches in the insulating layer and the opening5202 (as shown in FIG. 46A) with a layer of conductive material. In oneembodiment, a base layer (not shown) is first deposited on the internalsidewalls and bottom of the trenches and the opening 5202, and then theconductive layer is deposited on the base layer. In one embodiment, thebase layer includes a conductive seed layer (not shown) deposited on aconductive barrier layer (not shown). The seed layer can include copper,and the conductive barrier layer can include aluminum, titanium,tantalum, tantalum nitride, and the like metals. The conductive barrierlayer can be used to prevent diffusion of the conductive material fromthe seed layer, e.g., copper, into the insulating layer. Additionally,the conductive barrier layer can be used to provide adhesion for theseed layer (e.g., copper or cobalt).

In one embodiment, to form the base layer, the conductive barrier layeris deposited onto the sidewalls and bottom of the trenches, and then theseed layer is deposited on the conductive barrier layer. In anotherembodiment, the conductive base layer includes the seed layer that isdirectly deposited onto the sidewalls and bottom of the trenches. Eachof the conductive barrier layer and seed layer may be deposited usingany thin film deposition technique known to one of ordinary skill in theart of semiconductor manufacturing, e.g., sputtering, blanketdeposition, and the like. In one embodiment, each of the conductivebarrier layer and the seed layer has the thickness in an approximaterange from about 1 nm to about 100 nm. In one embodiment, the barrierlayer may be a thin dielectric that has been etched to establishconductivity to the metal layer below. In one embodiment, the barrierlayer may be omitted altogether and appropriate doping of the copperline may be used to make a “self-forming barrier”.

In one embodiment, the conductive layer e.g., copper, is deposited ontothe seed layer of base later of copper, by an electroplating process. Inone embodiment, the conductive layer is deposited into the trenchesusing a damascene process known to one of ordinary skill in the art ofmicroelectronic device manufacturing. In one embodiment, the conductivelayer is deposited onto the seed layer in the trenches and in theopening 5202 using a selective deposition technique, such as but notlimited to electroplating, electrolysis, a CVD, PVD, MBE, MOCVD, ALD,spin-on, or other deposition techniques known to one of ordinary skillin the art of microelectronic device manufacturing.

In one embodiment, the choice of a material for conductive layer for theconductive lines 5302 and via 5324 determines the choice of a materialfor the seed layer. For example, if the material for the conductivelines 5302 and via 5324 includes copper, the material for the seed layeralso includes copper. In one embodiment, the conductive lines 5302 andvia 5324 include a metal, for example, copper (Cu), ruthenium (Ru),nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), manganese (Mn),titanium (Ti), aluminum (Al), hafnium (Hf), tantalum (Ta), tungsten (W),vanadium (V), molybdenum (Mo), palladium (Pd), gold (Au), silver (Ag),platinum (Pt), indium (In), tin (Sn), lead (Pb), antimony (Sb), bismuth(Bi), zinc (Zn), cadmium (Cd), or any combination thereof.

In alternative embodiments, examples of the conductive materials thatmay be used for the conductive lines 5302 and via 5324 are, but notlimited to, metals, e.g., copper, tantalum, tungsten, ruthenium,titanium, hafnium, zirconium, aluminum, silver, tin, lead, metal alloys,metal carbides, e.g., hafnium carbide, zirconium carbide, titaniumcarbide, tantalum carbide, aluminum carbide, other conductive materials,or any combination thereof.

In one embodiment, portions of the conductive layer and the base layerare removed to even out top portions of the conductive lines 5302 withtop portions of the insulating layer 4102 using a chemical-mechanicalpolishing (“CMP”) technique known to one of ordinary skill in the art ofmicroelectronic device manufacturing.

In one non-limiting example, the thickness of the conductive lines 5302is in an approximate range from about 15 nm to about 1000 nm. In onenon-limiting example, the thickness of the conductive lines 5302 is fromabout 20 nm to about 200 nm. In one non-limiting example, the width ofthe conductive lines 5302 is in an approximate range from about 5 nm toabout 500 nm. In one non-limiting example, the spacing (pitch) betweenthe conductive lines 5302 is from about 2 nm to about 500 nm. In morespecific non-limiting example, the spacing (pitch) between theconductive lines 5302 is from about 5 nm to about 50 nm.

In an embodiment, the upper metallization layer My is configured toconnect to other metallization layers (not shown). In an embodiment, themetallization layer My is configures to provide electrical contact toelectronic devices, e.g., transistors, memories, capacitors, resistors,optoelectronic devices, switches, and any other active and passiveelectronic devices that are separated by an electrically insulatinglayer, for example, an interlayer dielectric, a trench insulation layer,or any other insulating layer known to one or ordinary skill in the artof electronic device manufacturing.

In the foregoing specification, embodiments of the disclosure have beendescribed with reference to specific exemplary embodiments thereof. Itwill be evident that various modifications may be made thereto withoutdeparting from the broader spirit and scope of the embodiments of thedisclosure as set forth in the following claims. The specification anddrawings are, accordingly, to be regarded in an illustrative senserather than a restrictive sense.

What is claimed is:
 1. A method to provide a self-aligned via, themethod comprising: providing a substrate having a first insulating layerthereon, the first insulating layer having a top surface with trenchesformed along a first direction; forming a cap layer on the top surfaceof the first insulating layer; providing recessed first conductive linesin the trenches of the first insulating layer, the recessed firstconductive lines extending along the first direction and having a firstconductive surface below the top surface of the first insulating layer;forming a first metal film on the recessed first conductive lines;forming pillars from the first metal film on the recessed firstconductive lines, the pillars extending orthogonal to the top surface ofthe first insulating layer; selectively removing at least a portion ofthe cap layer to expose the top surface of the first insulating layer;depositing a second insulating layer around the pillars and on the topsurface of the first insulating layer; selectively removing at least oneof the pillars to form at least one opening in the second insulatinglayer; depositing a third insulating layer in the at least one openingonto the recessed first conductive lines to form filled vias; etching aportion of the third insulating layer relative to the second insulatinglayer to form a via opening to at least one of the recessed firstconductive lines; and forming second conductive lines on portions of thesecond insulating layer and the third insulating layer, the secondconductive lines extending along a second direction that crosses thefirst direction at an angle.
 2. The method of claim 1, whereinselectively removing at least a portion of the cap layer comprisesexposing the substrate to a solution of hot phosphoric acid.
 3. Themethod of claim 2, wherein the entirety of the cap layer is removed. 4.The method of claim 1, further comprising depositing an etch stop layerbetween the cap layer and the first insulating layer.
 5. The method ofclaim 4, wherein the etch stop layer is selected from aluminum oxide(Al₂O₃), hafnium dioxide (HfO₂), and combinations thereof.
 6. The methodof claim 1, wherein the recessed first conductive lines and secondconductive lines independently comprise one or more of copper,ruthenium, nickel, cobalt, chromium, iron, manganese, titanium,aluminum, hafnium, tantalum, tungsten, vanadium, molybdenum, palladium,gold, silver, platinum, indium, tin, lead, antimony, bismuth, zinc, orcadmium.
 7. The method of claim 6, wherein the recessed first conductivelines and the second conductive lines independently comprise one or moreof copper or cobalt.
 8. The method of claim 1, wherein the cap layercomprises one or more of silicon nitride, silicon oxide, siliconoxynitride, and silicon carbonitride.
 9. The method of claim 1, whereinthe first metal film comprises tungsten and wherein the pillars areformed by oxidizing the first metal film to form tungsten oxide.
 10. Themethod of claim 1, wherein the recessed first conductive lines have awidth in a range of about 2 nm to about 15 nm.
 11. The method of claim1, wherein the first insulating layer, the second insulating layer, andthe third insulating layer are independently selected from: oxides,carbon doped oxides, porous silicon dioxide, carbides, oxycarbides,nitrides, oxynitrides, oxycarbonitrides, polymers, phosphosilicateglass, fluorosilicate (SiOF) glass, organosilicate glass (SiOCH), or anycombinations thereof.
 12. The method of claim 1, wherein the firstinsulating layer and the second insulating layer are comprised of thesame material.
 13. The method of claim 1, wherein the recessed firstconductive lines are recessed in a range of about 10 nm to about 50 nm.14. The method of claim 1, wherein the pillars are removed by etchingwith a solution of HF and HNO₃, a solution of NH₄OH and H₂O₂, WCl₅, WF₆.15. A method to provide a self-aligned via, the method comprising:providing a substrate having a first insulating layer thereon, the firstinsulating layer having a top surface with trenches formed along a firstdirection; forming a cap layer on the top surface of the firstinsulating layer, the cap layer comprising one or more of siliconnitride, silicon oxide, silicon oxynitride, and silicon carbonitride;providing recessed first conductive lines in the trenches of the firstinsulating layer, the recessed first conductive lines extending alongthe first direction and having a first conductive surface below the topsurface of the first insulating layer, the recessed first conductivelines comprising one or more of copper or cobalt; forming a first metalfilm on the recessed first conductive lines, the first metal filmcomprising tungsten; forming pillars from the first metal film on therecessed first conductive lines, the pillars extending orthogonal to thetop surface of the first insulating layer; selectively removing at leasta portion of the cap layer to expose the top surface of the firstinsulating layer by exposing the substrate to a solution of hotphosphoric acid; depositing a second insulating layer around the pillarsand on the top surface of the first insulating layer, the secondinsulating layer comprising a flowable silicon oxide; planarizing thesecond insulating layer to expose tops of the pillars; selectivelyremoving at least one of the pillars to form at least one opening in thesecond insulating layer; depositing a third insulating layer in the atleast one opening onto the recessed first conductive lines to formfilled vias, the third insulating layer comprising a flowable siliconoxide; etching a portion of the third insulating layer relative to thesecond insulating layer to form a via opening to at least one of therecessed first conductive lines; and forming second conductive lines onportions of the second insulating layer and the third insulating layer,the second conductive lines extending along a second direction thatcrosses the first direction at an angle, the second conductive linescomprising one or more of copper or cobalt.